Adding upstream version 3.40.1.upstream/3.40.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2277 insertions, 0 deletions

diff --git a/src/alter.c b/src/alter.c
new file mode 100644
index 0000000..d8a9982
--- /dev/null
+++ b/src/alter.c
@@ -0,0 +1,2277 @@
+/*
+** 2005 February 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that used to generate VDBE code
+** that implements the ALTER TABLE command.
+*/
+#include "sqliteInt.h"
+
+/*
+** The code in this file only exists if we are not omitting the
+** ALTER TABLE logic from the build.
+*/
+#ifndef SQLITE_OMIT_ALTERTABLE
+
+/*
+** Parameter zName is the name of a table that is about to be altered
+** (either with ALTER TABLE ... RENAME TO or ALTER TABLE ... ADD COLUMN).
+** If the table is a system table, this function leaves an error message
+** in pParse->zErr (system tables may not be altered) and returns non-zero.
+**
+** Or, if zName is not a system table, zero is returned.
+*/
+static int isAlterableTable(Parse *pParse, Table *pTab){
+  if( 0==sqlite3StrNICmp(pTab->zName, "sqlite_", 7)
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+   || (pTab->tabFlags & TF_Eponymous)!=0
+   || ( (pTab->tabFlags & TF_Shadow)!=0
+        && sqlite3ReadOnlyShadowTables(pParse->db)
+   )
+#endif
+  ){
+    sqlite3ErrorMsg(pParse, "table %s may not be altered", pTab->zName);
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** Generate code to verify that the schemas of database zDb and, if
+** bTemp is not true, database "temp", can still be parsed. This is
+** called at the end of the generation of an ALTER TABLE ... RENAME ...
+** statement to ensure that the operation has not rendered any schema
+** objects unusable.
+*/
+static void renameTestSchema(
+  Parse *pParse,                  /* Parse context */
+  const char *zDb,                /* Name of db to verify schema of */
+  int bTemp,                      /* True if this is the temp db */
+  const char *zWhen,              /* "when" part of error message */
+  int bNoDQS                      /* Do not allow DQS in the schema */
+){
+  pParse->colNamesSet = 1;
+  sqlite3NestedParse(pParse, 
+      "SELECT 1 "
+      "FROM \"%w\"." LEGACY_SCHEMA_TABLE " "
+      "WHERE name NOT LIKE 'sqliteX_%%' ESCAPE 'X'"
+      " AND sql NOT LIKE 'create virtual%%'"
+      " AND sqlite_rename_test(%Q, sql, type, name, %d, %Q, %d)=NULL ",
+      zDb,
+      zDb, bTemp, zWhen, bNoDQS
+  );
+
+  if( bTemp==0 ){
+    sqlite3NestedParse(pParse, 
+        "SELECT 1 "
+        "FROM temp." LEGACY_SCHEMA_TABLE " "
+        "WHERE name NOT LIKE 'sqliteX_%%' ESCAPE 'X'"
+        " AND sql NOT LIKE 'create virtual%%'"
+        " AND sqlite_rename_test(%Q, sql, type, name, 1, %Q, %d)=NULL ",
+        zDb, zWhen, bNoDQS
+    );
+  }
+}
+
+/*
+** Generate VM code to replace any double-quoted strings (but not double-quoted
+** identifiers) within the "sql" column of the sqlite_schema table in 
+** database zDb with their single-quoted equivalents. If argument bTemp is
+** not true, similarly update all SQL statements in the sqlite_schema table
+** of the temp db.
+*/
+static void renameFixQuotes(Parse *pParse, const char *zDb, int bTemp){
+  sqlite3NestedParse(pParse, 
+      "UPDATE \"%w\"." LEGACY_SCHEMA_TABLE 
+      " SET sql = sqlite_rename_quotefix(%Q, sql)"
+      "WHERE name NOT LIKE 'sqliteX_%%' ESCAPE 'X'"
+      " AND sql NOT LIKE 'create virtual%%'" , zDb, zDb
+  );
+  if( bTemp==0 ){
+    sqlite3NestedParse(pParse, 
+      "UPDATE temp." LEGACY_SCHEMA_TABLE
+      " SET sql = sqlite_rename_quotefix('temp', sql)"
+      "WHERE name NOT LIKE 'sqliteX_%%' ESCAPE 'X'"
+      " AND sql NOT LIKE 'create virtual%%'"
+    );
+  }
+}
+
+/*
+** Generate code to reload the schema for database iDb. And, if iDb!=1, for
+** the temp database as well.
+*/
+static void renameReloadSchema(Parse *pParse, int iDb, u16 p5){
+  Vdbe *v = pParse->pVdbe;
+  if( v ){
+    sqlite3ChangeCookie(pParse, iDb);
+    sqlite3VdbeAddParseSchemaOp(pParse->pVdbe, iDb, 0, p5);
+    if( iDb!=1 ) sqlite3VdbeAddParseSchemaOp(pParse->pVdbe, 1, 0, p5);
+  }
+}
+
+/*
+** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy" 
+** command. 
+*/
+void sqlite3AlterRenameTable(
+  Parse *pParse,            /* Parser context. */
+  SrcList *pSrc,            /* The table to rename. */
+  Token *pName              /* The new table name. */
+){
+  int iDb;                  /* Database that contains the table */
+  char *zDb;                /* Name of database iDb */
+  Table *pTab;              /* Table being renamed */
+  char *zName = 0;          /* NULL-terminated version of pName */ 
+  sqlite3 *db = pParse->db; /* Database connection */
+  int nTabName;             /* Number of UTF-8 characters in zTabName */
+  const char *zTabName;     /* Original name of the table */
+  Vdbe *v;
+  VTable *pVTab = 0;        /* Non-zero if this is a v-tab with an xRename() */
+
+  if( NEVER(db->mallocFailed) ) goto exit_rename_table;
+  assert( pSrc->nSrc==1 );
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_rename_table;
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  zDb = db->aDb[iDb].zDbSName;
+
+  /* Get a NULL terminated version of the new table name. */
+  zName = sqlite3NameFromToken(db, pName);
+  if( !zName ) goto exit_rename_table;
+
+  /* Check that a table or index named 'zName' does not already exist
+  ** in database iDb. If so, this is an error.
+  */
+  if( sqlite3FindTable(db, zName, zDb)
+   || sqlite3FindIndex(db, zName, zDb)
+   || sqlite3IsShadowTableOf(db, pTab, zName)
+  ){
+    sqlite3ErrorMsg(pParse, 
+        "there is already another table or index with this name: %s", zName);
+    goto exit_rename_table;
+  }
+
+  /* Make sure it is not a system table being altered, or a reserved name
+  ** that the table is being renamed to.
+  */
+  if( SQLITE_OK!=isAlterableTable(pParse, pTab) ){
+    goto exit_rename_table;
+  }
+  if( SQLITE_OK!=sqlite3CheckObjectName(pParse,zName,"table",zName) ){
+    goto exit_rename_table;
+  }
+
+#ifndef SQLITE_OMIT_VIEW
+  if( IsView(pTab) ){
+    sqlite3ErrorMsg(pParse, "view %s may not be altered", pTab->zName);
+    goto exit_rename_table;
+  }
+#endif
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
+    goto exit_rename_table;
+  }
+#endif
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto exit_rename_table;
+  }
+  if( IsVirtual(pTab) ){
+    pVTab = sqlite3GetVTable(db, pTab);
+    if( pVTab->pVtab->pModule->xRename==0 ){
+      pVTab = 0;
+    }
+  }
+#endif
+
+  /* Begin a transaction for database iDb. Then modify the schema cookie
+  ** (since the ALTER TABLE modifies the schema). Call sqlite3MayAbort(),
+  ** as the scalar functions (e.g. sqlite_rename_table()) invoked by the 
+  ** nested SQL may raise an exception.  */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ){
+    goto exit_rename_table;
+  }
+  sqlite3MayAbort(pParse);
+
+  /* figure out how many UTF-8 characters are in zName */
+  zTabName = pTab->zName;
+  nTabName = sqlite3Utf8CharLen(zTabName, -1);
+
+  /* Rewrite all CREATE TABLE, INDEX, TRIGGER or VIEW statements in
+  ** the schema to use the new table name.  */
+  sqlite3NestedParse(pParse, 
+      "UPDATE \"%w\"." LEGACY_SCHEMA_TABLE " SET "
+      "sql = sqlite_rename_table(%Q, type, name, sql, %Q, %Q, %d) "
+      "WHERE (type!='index' OR tbl_name=%Q COLLATE nocase)"
+      "AND   name NOT LIKE 'sqliteX_%%' ESCAPE 'X'"
+      , zDb, zDb, zTabName, zName, (iDb==1), zTabName
+  );
+
+  /* Update the tbl_name and name columns of the sqlite_schema table
+  ** as required.  */
+  sqlite3NestedParse(pParse,
+      "UPDATE %Q." LEGACY_SCHEMA_TABLE " SET "
+          "tbl_name = %Q, "
+          "name = CASE "
+            "WHEN type='table' THEN %Q "
+            "WHEN name LIKE 'sqliteX_autoindex%%' ESCAPE 'X' "
+            "     AND type='index' THEN "
+             "'sqlite_autoindex_' || %Q || substr(name,%d+18) "
+            "ELSE name END "
+      "WHERE tbl_name=%Q COLLATE nocase AND "
+          "(type='table' OR type='index' OR type='trigger');", 
+      zDb,
+      zName, zName, zName, 
+      nTabName, zTabName
+  );
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+  /* If the sqlite_sequence table exists in this database, then update 
+  ** it with the new table name.
+  */
+  if( sqlite3FindTable(db, "sqlite_sequence", zDb) ){
+    sqlite3NestedParse(pParse,
+        "UPDATE \"%w\".sqlite_sequence set name = %Q WHERE name = %Q",
+        zDb, zName, pTab->zName);
+  }
+#endif
+
+  /* If the table being renamed is not itself part of the temp database,
+  ** edit view and trigger definitions within the temp database 
+  ** as required.  */
+  if( iDb!=1 ){
+    sqlite3NestedParse(pParse, 
+        "UPDATE sqlite_temp_schema SET "
+            "sql = sqlite_rename_table(%Q, type, name, sql, %Q, %Q, 1), "
+            "tbl_name = "
+              "CASE WHEN tbl_name=%Q COLLATE nocase AND "
+              "  sqlite_rename_test(%Q, sql, type, name, 1, 'after rename', 0) "
+              "THEN %Q ELSE tbl_name END "
+            "WHERE type IN ('view', 'trigger')"
+        , zDb, zTabName, zName, zTabName, zDb, zName);
+  }
+
+  /* If this is a virtual table, invoke the xRename() function if
+  ** one is defined. The xRename() callback will modify the names
+  ** of any resources used by the v-table implementation (including other
+  ** SQLite tables) that are identified by the name of the virtual table.
+  */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( pVTab ){
+    int i = ++pParse->nMem;
+    sqlite3VdbeLoadString(v, i, zName);
+    sqlite3VdbeAddOp4(v, OP_VRename, i, 0, 0,(const char*)pVTab, P4_VTAB);
+  }
+#endif
+
+  renameReloadSchema(pParse, iDb, INITFLAG_AlterRename);
+  renameTestSchema(pParse, zDb, iDb==1, "after rename", 0);
+
+exit_rename_table:
+  sqlite3SrcListDelete(db, pSrc);
+  sqlite3DbFree(db, zName);
+}
+
+/*
+** Write code that will raise an error if the table described by
+** zDb and zTab is not empty.
+*/
+static void sqlite3ErrorIfNotEmpty(
+  Parse *pParse,        /* Parsing context */
+  const char *zDb,      /* Schema holding the table */
+  const char *zTab,     /* Table to check for empty */
+  const char *zErr      /* Error message text */
+){
+  sqlite3NestedParse(pParse,
+     "SELECT raise(ABORT,%Q) FROM \"%w\".\"%w\"",
+     zErr, zDb, zTab
+  );
+}
+
+/*
+** This function is called after an "ALTER TABLE ... ADD" statement
+** has been parsed. Argument pColDef contains the text of the new
+** column definition.
+**
+** The Table structure pParse->pNewTable was extended to include
+** the new column during parsing.
+*/
+void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
+  Table *pNew;              /* Copy of pParse->pNewTable */
+  Table *pTab;              /* Table being altered */
+  int iDb;                  /* Database number */
+  const char *zDb;          /* Database name */
+  const char *zTab;         /* Table name */
+  char *zCol;               /* Null-terminated column definition */
+  Column *pCol;             /* The new column */
+  Expr *pDflt;              /* Default value for the new column */
+  sqlite3 *db;              /* The database connection; */
+  Vdbe *v;                  /* The prepared statement under construction */
+  int r1;                   /* Temporary registers */
+
+  db = pParse->db;
+  assert( db->pParse==pParse );
+  if( pParse->nErr ) return;
+  assert( db->mallocFailed==0 );
+  pNew = pParse->pNewTable;
+  assert( pNew );
+
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  iDb = sqlite3SchemaToIndex(db, pNew->pSchema);
+  zDb = db->aDb[iDb].zDbSName;
+  zTab = &pNew->zName[16];  /* Skip the "sqlite_altertab_" prefix on the name */
+  pCol = &pNew->aCol[pNew->nCol-1];
+  pDflt = sqlite3ColumnExpr(pNew, pCol);
+  pTab = sqlite3FindTable(db, zTab, zDb);
+  assert( pTab );
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
+    return;
+  }
+#endif
+
+
+  /* Check that the new column is not specified as PRIMARY KEY or UNIQUE.
+  ** If there is a NOT NULL constraint, then the default value for the
+  ** column must not be NULL.
+  */
+  if( pCol->colFlags & COLFLAG_PRIMKEY ){
+    sqlite3ErrorMsg(pParse, "Cannot add a PRIMARY KEY column");
+    return;
+  }
+  if( pNew->pIndex ){
+    sqlite3ErrorMsg(pParse,
+         "Cannot add a UNIQUE column");
+    return;
+  }
+  if( (pCol->colFlags & COLFLAG_GENERATED)==0 ){
+    /* If the default value for the new column was specified with a 
+    ** literal NULL, then set pDflt to 0. This simplifies checking
+    ** for an SQL NULL default below.
+    */
+    assert( pDflt==0 || pDflt->op==TK_SPAN );
+    if( pDflt && pDflt->pLeft->op==TK_NULL ){
+      pDflt = 0;
+    }
+    assert( IsOrdinaryTable(pNew) );
+    if( (db->flags&SQLITE_ForeignKeys) && pNew->u.tab.pFKey && pDflt ){
+      sqlite3ErrorIfNotEmpty(pParse, zDb, zTab,
+          "Cannot add a REFERENCES column with non-NULL default value");
+    }
+    if( pCol->notNull && !pDflt ){
+      sqlite3ErrorIfNotEmpty(pParse, zDb, zTab,
+          "Cannot add a NOT NULL column with default value NULL");
+    }
+
+
+    /* Ensure the default expression is something that sqlite3ValueFromExpr()
+    ** can handle (i.e. not CURRENT_TIME etc.)
+    */
+    if( pDflt ){
+      sqlite3_value *pVal = 0;
+      int rc;
+      rc = sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_BLOB, &pVal);
+      assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+      if( rc!=SQLITE_OK ){
+        assert( db->mallocFailed == 1 );
+        return;
+      }
+      if( !pVal ){
+        sqlite3ErrorIfNotEmpty(pParse, zDb, zTab,
+           "Cannot add a column with non-constant default");
+      }
+      sqlite3ValueFree(pVal);
+    }
+  }else if( pCol->colFlags & COLFLAG_STORED ){
+    sqlite3ErrorIfNotEmpty(pParse, zDb, zTab, "cannot add a STORED column");
+  }
+
+
+  /* Modify the CREATE TABLE statement. */
+  zCol = sqlite3DbStrNDup(db, (char*)pColDef->z, pColDef->n);
+  if( zCol ){
+    char *zEnd = &zCol[pColDef->n-1];
+    while( zEnd>zCol && (*zEnd==';' || sqlite3Isspace(*zEnd)) ){
+      *zEnd-- = '\0';
+    }
+    /* substr() operations on characters, but addColOffset is in bytes. So we
+    ** have to use printf() to translate between these units: */
+    assert( IsOrdinaryTable(pTab) );
+    assert( IsOrdinaryTable(pNew) );
+    sqlite3NestedParse(pParse, 
+        "UPDATE \"%w\"." LEGACY_SCHEMA_TABLE " SET "
+          "sql = printf('%%.%ds, ',sql) || %Q"
+          " || substr(sql,1+length(printf('%%.%ds',sql))) "
+        "WHERE type = 'table' AND name = %Q", 
+      zDb, pNew->u.tab.addColOffset, zCol, pNew->u.tab.addColOffset,
+      zTab
+    );
+    sqlite3DbFree(db, zCol);
+  }
+
+  v = sqlite3GetVdbe(pParse);
+  if( v ){
+    /* Make sure the schema version is at least 3.  But do not upgrade
+    ** from less than 3 to 4, as that will corrupt any preexisting DESC
+    ** index.
+    */
+    r1 = sqlite3GetTempReg(pParse);
+    sqlite3VdbeAddOp3(v, OP_ReadCookie, iDb, r1, BTREE_FILE_FORMAT);
+    sqlite3VdbeUsesBtree(v, iDb);
+    sqlite3VdbeAddOp2(v, OP_AddImm, r1, -2);
+    sqlite3VdbeAddOp2(v, OP_IfPos, r1, sqlite3VdbeCurrentAddr(v)+2);
+    VdbeCoverage(v);
+    sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_FILE_FORMAT, 3);
+    sqlite3ReleaseTempReg(pParse, r1);
+
+    /* Reload the table definition */
+    renameReloadSchema(pParse, iDb, INITFLAG_AlterAdd);
+
+    /* Verify that constraints are still satisfied */
+    if( pNew->pCheck!=0
+     || (pCol->notNull && (pCol->colFlags & COLFLAG_GENERATED)!=0)
+    ){
+      sqlite3NestedParse(pParse,
+        "SELECT CASE WHEN quick_check GLOB 'CHECK*'"
+        " THEN raise(ABORT,'CHECK constraint failed')"
+        " ELSE raise(ABORT,'NOT NULL constraint failed')"
+        " END"
+        "  FROM pragma_quick_check(%Q,%Q)"
+        " WHERE quick_check GLOB 'CHECK*' OR quick_check GLOB 'NULL*'",
+        zTab, zDb
+      );
+    }
+  }
+}
+
+/*
+** This function is called by the parser after the table-name in
+** an "ALTER TABLE <table-name> ADD" statement is parsed. Argument 
+** pSrc is the full-name of the table being altered.
+**
+** This routine makes a (partial) copy of the Table structure
+** for the table being altered and sets Parse.pNewTable to point
+** to it. Routines called by the parser as the column definition
+** is parsed (i.e. sqlite3AddColumn()) add the new Column data to 
+** the copy. The copy of the Table structure is deleted by tokenize.c 
+** after parsing is finished.
+**
+** Routine sqlite3AlterFinishAddColumn() will be called to complete
+** coding the "ALTER TABLE ... ADD" statement.
+*/
+void sqlite3AlterBeginAddColumn(Parse *pParse, SrcList *pSrc){
+  Table *pNew;
+  Table *pTab;
+  int iDb;
+  int i;
+  int nAlloc;
+  sqlite3 *db = pParse->db;
+
+  /* Look up the table being altered. */
+  assert( pParse->pNewTable==0 );
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  if( db->mallocFailed ) goto exit_begin_add_column;
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_begin_add_column;
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( IsVirtual(pTab) ){
+    sqlite3ErrorMsg(pParse, "virtual tables may not be altered");
+    goto exit_begin_add_column;
+  }
+#endif
+
+  /* Make sure this is not an attempt to ALTER a view. */
+  if( IsView(pTab) ){
+    sqlite3ErrorMsg(pParse, "Cannot add a column to a view");
+    goto exit_begin_add_column;
+  }
+  if( SQLITE_OK!=isAlterableTable(pParse, pTab) ){
+    goto exit_begin_add_column;
+  }
+
+  sqlite3MayAbort(pParse);
+  assert( IsOrdinaryTable(pTab) );
+  assert( pTab->u.tab.addColOffset>0 );
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+
+  /* Put a copy of the Table struct in Parse.pNewTable for the
+  ** sqlite3AddColumn() function and friends to modify.  But modify
+  ** the name by adding an "sqlite_altertab_" prefix.  By adding this
+  ** prefix, we insure that the name will not collide with an existing
+  ** table because user table are not allowed to have the "sqlite_"
+  ** prefix on their name.
+  */
+  pNew = (Table*)sqlite3DbMallocZero(db, sizeof(Table));
+  if( !pNew ) goto exit_begin_add_column;
+  pParse->pNewTable = pNew;
+  pNew->nTabRef = 1;
+  pNew->nCol = pTab->nCol;
+  assert( pNew->nCol>0 );
+  nAlloc = (((pNew->nCol-1)/8)*8)+8;
+  assert( nAlloc>=pNew->nCol && nAlloc%8==0 && nAlloc-pNew->nCol<8 );
+  pNew->aCol = (Column*)sqlite3DbMallocZero(db, sizeof(Column)*nAlloc);
+  pNew->zName = sqlite3MPrintf(db, "sqlite_altertab_%s", pTab->zName);
+  if( !pNew->aCol || !pNew->zName ){
+    assert( db->mallocFailed );
+    goto exit_begin_add_column;
+  }
+  memcpy(pNew->aCol, pTab->aCol, sizeof(Column)*pNew->nCol);
+  for(i=0; i<pNew->nCol; i++){
+    Column *pCol = &pNew->aCol[i];
+    pCol->zCnName = sqlite3DbStrDup(db, pCol->zCnName);
+    pCol->hName = sqlite3StrIHash(pCol->zCnName);
+  }
+  assert( IsOrdinaryTable(pNew) );
+  pNew->u.tab.pDfltList = sqlite3ExprListDup(db, pTab->u.tab.pDfltList, 0);
+  pNew->pSchema = db->aDb[iDb].pSchema;
+  pNew->u.tab.addColOffset = pTab->u.tab.addColOffset;
+  pNew->nTabRef = 1;
+
+exit_begin_add_column:
+  sqlite3SrcListDelete(db, pSrc);
+  return;
+}
+
+/*
+** Parameter pTab is the subject of an ALTER TABLE ... RENAME COLUMN
+** command. This function checks if the table is a view or virtual
+** table (columns of views or virtual tables may not be renamed). If so,
+** it loads an error message into pParse and returns non-zero.
+**
+** Or, if pTab is not a view or virtual table, zero is returned.
+*/
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
+static int isRealTable(Parse *pParse, Table *pTab, int bDrop){
+  const char *zType = 0;
+#ifndef SQLITE_OMIT_VIEW
+  if( IsView(pTab) ){
+    zType = "view";
+  }
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( IsVirtual(pTab) ){
+    zType = "virtual table";
+  }
+#endif
+  if( zType ){
+    sqlite3ErrorMsg(pParse, "cannot %s %s \"%s\"", 
+        (bDrop ? "drop column from" : "rename columns of"),
+        zType, pTab->zName
+    );
+    return 1;
+  }
+  return 0;
+}
+#else /* !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE) */
+# define isRealTable(x,y,z) (0)
+#endif
+
+/*
+** Handles the following parser reduction:
+**
+**  cmd ::= ALTER TABLE pSrc RENAME COLUMN pOld TO pNew
+*/
+void sqlite3AlterRenameColumn(
+  Parse *pParse,                  /* Parsing context */
+  SrcList *pSrc,                  /* Table being altered.  pSrc->nSrc==1 */
+  Token *pOld,                    /* Name of column being changed */
+  Token *pNew                     /* New column name */
+){
+  sqlite3 *db = pParse->db;       /* Database connection */
+  Table *pTab;                    /* Table being updated */
+  int iCol;                       /* Index of column being renamed */
+  char *zOld = 0;                 /* Old column name */
+  char *zNew = 0;                 /* New column name */
+  const char *zDb;                /* Name of schema containing the table */
+  int iSchema;                    /* Index of the schema */
+  int bQuote;                     /* True to quote the new name */
+
+  /* Locate the table to be altered */
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_rename_column;
+
+  /* Cannot alter a system table */
+  if( SQLITE_OK!=isAlterableTable(pParse, pTab) ) goto exit_rename_column;
+  if( SQLITE_OK!=isRealTable(pParse, pTab, 0) ) goto exit_rename_column;
+
+  /* Which schema holds the table to be altered */  
+  iSchema = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iSchema>=0 );
+  zDb = db->aDb[iSchema].zDbSName;
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
+    goto exit_rename_column;
+  }
+#endif
+
+  /* Make sure the old name really is a column name in the table to be
+  ** altered.  Set iCol to be the index of the column being renamed */
+  zOld = sqlite3NameFromToken(db, pOld);
+  if( !zOld ) goto exit_rename_column;
+  for(iCol=0; iCol<pTab->nCol; iCol++){
+    if( 0==sqlite3StrICmp(pTab->aCol[iCol].zCnName, zOld) ) break;
+  }
+  if( iCol==pTab->nCol ){
+    sqlite3ErrorMsg(pParse, "no such column: \"%T\"", pOld);
+    goto exit_rename_column;
+  }
+
+  /* Ensure the schema contains no double-quoted strings */
+  renameTestSchema(pParse, zDb, iSchema==1, "", 0);
+  renameFixQuotes(pParse, zDb, iSchema==1);
+
+  /* Do the rename operation using a recursive UPDATE statement that
+  ** uses the sqlite_rename_column() SQL function to compute the new
+  ** CREATE statement text for the sqlite_schema table.
+  */
+  sqlite3MayAbort(pParse);
+  zNew = sqlite3NameFromToken(db, pNew);
+  if( !zNew ) goto exit_rename_column;
+  assert( pNew->n>0 );
+  bQuote = sqlite3Isquote(pNew->z[0]);
+  sqlite3NestedParse(pParse, 
+      "UPDATE \"%w\"." LEGACY_SCHEMA_TABLE " SET "
+      "sql = sqlite_rename_column(sql, type, name, %Q, %Q, %d, %Q, %d, %d) "
+      "WHERE name NOT LIKE 'sqliteX_%%' ESCAPE 'X' "
+      " AND (type != 'index' OR tbl_name = %Q)",
+      zDb,
+      zDb, pTab->zName, iCol, zNew, bQuote, iSchema==1,
+      pTab->zName
+  );
+
+  sqlite3NestedParse(pParse, 
+      "UPDATE temp." LEGACY_SCHEMA_TABLE " SET "
+      "sql = sqlite_rename_column(sql, type, name, %Q, %Q, %d, %Q, %d, 1) "
+      "WHERE type IN ('trigger', 'view')",
+      zDb, pTab->zName, iCol, zNew, bQuote
+  );
+
+  /* Drop and reload the database schema. */
+  renameReloadSchema(pParse, iSchema, INITFLAG_AlterRename);
+  renameTestSchema(pParse, zDb, iSchema==1, "after rename", 1);
+
+ exit_rename_column:
+  sqlite3SrcListDelete(db, pSrc);
+  sqlite3DbFree(db, zOld);
+  sqlite3DbFree(db, zNew);
+  return;
+}
+
+/*
+** Each RenameToken object maps an element of the parse tree into
+** the token that generated that element.  The parse tree element
+** might be one of:
+**
+**     *  A pointer to an Expr that represents an ID
+**     *  The name of a table column in Column.zName
+**
+** A list of RenameToken objects can be constructed during parsing.
+** Each new object is created by sqlite3RenameTokenMap().
+** As the parse tree is transformed, the sqlite3RenameTokenRemap()
+** routine is used to keep the mapping current.
+**
+** After the parse finishes, renameTokenFind() routine can be used
+** to look up the actual token value that created some element in
+** the parse tree.
+*/
+struct RenameToken {
+  const void *p;         /* Parse tree element created by token t */
+  Token t;               /* The token that created parse tree element p */
+  RenameToken *pNext;    /* Next is a list of all RenameToken objects */
+};
+
+/*
+** The context of an ALTER TABLE RENAME COLUMN operation that gets passed
+** down into the Walker.
+*/
+typedef struct RenameCtx RenameCtx;
+struct RenameCtx {
+  RenameToken *pList;             /* List of tokens to overwrite */
+  int nList;                      /* Number of tokens in pList */
+  int iCol;                       /* Index of column being renamed */
+  Table *pTab;                    /* Table being ALTERed */ 
+  const char *zOld;               /* Old column name */
+};
+
+#ifdef SQLITE_DEBUG
+/*
+** This function is only for debugging. It performs two tasks:
+**
+**   1. Checks that pointer pPtr does not already appear in the 
+**      rename-token list.
+**
+**   2. Dereferences each pointer in the rename-token list.
+**
+** The second is most effective when debugging under valgrind or
+** address-sanitizer or similar. If any of these pointers no longer 
+** point to valid objects, an exception is raised by the memory-checking 
+** tool.
+**
+** The point of this is to prevent comparisons of invalid pointer values.
+** Even though this always seems to work, it is undefined according to the
+** C standard. Example of undefined comparison:
+**
+**     sqlite3_free(x);
+**     if( x==y ) ...
+**
+** Technically, as x no longer points into a valid object or to the byte
+** following a valid object, it may not be used in comparison operations.
+*/
+static void renameTokenCheckAll(Parse *pParse, const void *pPtr){
+  assert( pParse==pParse->db->pParse );
+  assert( pParse->db->mallocFailed==0 || pParse->nErr!=0 );
+  if( pParse->nErr==0 ){
+    const RenameToken *p;
+    u8 i = 0;
+    for(p=pParse->pRename; p; p=p->pNext){
+      if( p->p ){
+        assert( p->p!=pPtr );
+        i += *(u8*)(p->p);
+      }
+    }
+  }
+}
+#else
+# define renameTokenCheckAll(x,y)
+#endif
+
+/*
+** Remember that the parser tree element pPtr was created using
+** the token pToken.
+**
+** In other words, construct a new RenameToken object and add it
+** to the list of RenameToken objects currently being built up
+** in pParse->pRename.
+**
+** The pPtr argument is returned so that this routine can be used
+** with tail recursion in tokenExpr() routine, for a small performance
+** improvement.
+*/
+const void *sqlite3RenameTokenMap(
+  Parse *pParse,
+  const void *pPtr,
+  const Token *pToken
+){
+  RenameToken *pNew;
+  assert( pPtr || pParse->db->mallocFailed );
+  renameTokenCheckAll(pParse, pPtr);
+  if( ALWAYS(pParse->eParseMode!=PARSE_MODE_UNMAP) ){
+    pNew = sqlite3DbMallocZero(pParse->db, sizeof(RenameToken));
+    if( pNew ){
+      pNew->p = pPtr;
+      pNew->t = *pToken;
+      pNew->pNext = pParse->pRename;
+      pParse->pRename = pNew;
+    }
+  }
+
+  return pPtr;
+}
+
+/*
+** It is assumed that there is already a RenameToken object associated
+** with parse tree element pFrom. This function remaps the associated token
+** to parse tree element pTo.
+*/
+void sqlite3RenameTokenRemap(Parse *pParse, const void *pTo, const void *pFrom){
+  RenameToken *p;
+  renameTokenCheckAll(pParse, pTo);
+  for(p=pParse->pRename; p; p=p->pNext){
+    if( p->p==pFrom ){
+      p->p = pTo;
+      break;
+    }
+  }
+}
+
+/*
+** Walker callback used by sqlite3RenameExprUnmap().
+*/
+static int renameUnmapExprCb(Walker *pWalker, Expr *pExpr){
+  Parse *pParse = pWalker->pParse;
+  sqlite3RenameTokenRemap(pParse, 0, (const void*)pExpr);
+  if( ExprUseYTab(pExpr) ){
+    sqlite3RenameTokenRemap(pParse, 0, (const void*)&pExpr->y.pTab);
+  }
+  return WRC_Continue;
+}
+
+/*
+** Iterate through the Select objects that are part of WITH clauses attached
+** to select statement pSelect.
+*/
+static void renameWalkWith(Walker *pWalker, Select *pSelect){
+  With *pWith = pSelect->pWith;
+  if( pWith ){
+    Parse *pParse = pWalker->pParse;
+    int i;
+    With *pCopy = 0;
+    assert( pWith->nCte>0 );
+    if( (pWith->a[0].pSelect->selFlags & SF_Expanded)==0 ){
+      /* Push a copy of the With object onto the with-stack. We use a copy
+      ** here as the original will be expanded and resolved (flags SF_Expanded
+      ** and SF_Resolved) below. And the parser code that uses the with-stack
+      ** fails if the Select objects on it have already been expanded and
+      ** resolved.  */
+      pCopy = sqlite3WithDup(pParse->db, pWith);
+      pCopy = sqlite3WithPush(pParse, pCopy, 1);
+    }
+    for(i=0; i<pWith->nCte; i++){
+      Select *p = pWith->a[i].pSelect;
+      NameContext sNC;
+      memset(&sNC, 0, sizeof(sNC));
+      sNC.pParse = pParse;
+      if( pCopy ) sqlite3SelectPrep(sNC.pParse, p, &sNC);
+      if( sNC.pParse->db->mallocFailed ) return;
+      sqlite3WalkSelect(pWalker, p);
+      sqlite3RenameExprlistUnmap(pParse, pWith->a[i].pCols);
+    }
+    if( pCopy && pParse->pWith==pCopy ){
+      pParse->pWith = pCopy->pOuter;
+    }
+  }
+}
+
+/*
+** Unmap all tokens in the IdList object passed as the second argument.
+*/
+static void unmapColumnIdlistNames(
+  Parse *pParse,
+  const IdList *pIdList
+){
+  int ii;
+  assert( pIdList!=0 );
+  for(ii=0; ii<pIdList->nId; ii++){
+    sqlite3RenameTokenRemap(pParse, 0, (const void*)pIdList->a[ii].zName);
+  }
+}
+
+/*
+** Walker callback used by sqlite3RenameExprUnmap().
+*/
+static int renameUnmapSelectCb(Walker *pWalker, Select *p){
+  Parse *pParse = pWalker->pParse;
+  int i;
+  if( pParse->nErr ) return WRC_Abort;
+  testcase( p->selFlags & SF_View );
+  testcase( p->selFlags & SF_CopyCte );
+  if( p->selFlags & (SF_View|SF_CopyCte) ){
+    return WRC_Prune;
+  }
+  if( ALWAYS(p->pEList) ){
+    ExprList *pList = p->pEList;
+    for(i=0; i<pList->nExpr; i++){
+      if( pList->a[i].zEName && pList->a[i].fg.eEName==ENAME_NAME ){
+        sqlite3RenameTokenRemap(pParse, 0, (void*)pList->a[i].zEName);
+      }
+    }
+  }
+  if( ALWAYS(p->pSrc) ){  /* Every Select as a SrcList, even if it is empty */
+    SrcList *pSrc = p->pSrc;
+    for(i=0; i<pSrc->nSrc; i++){
+      sqlite3RenameTokenRemap(pParse, 0, (void*)pSrc->a[i].zName);
+      if( pSrc->a[i].fg.isUsing==0 ){
+        sqlite3WalkExpr(pWalker, pSrc->a[i].u3.pOn);
+      }else{
+        unmapColumnIdlistNames(pParse, pSrc->a[i].u3.pUsing);
+      }
+    }
+  }
+
+  renameWalkWith(pWalker, p);
+  return WRC_Continue;
+}
+
+/*
+** Remove all nodes that are part of expression pExpr from the rename list.
+*/
+void sqlite3RenameExprUnmap(Parse *pParse, Expr *pExpr){
+  u8 eMode = pParse->eParseMode;
+  Walker sWalker;
+  memset(&sWalker, 0, sizeof(Walker));
+  sWalker.pParse = pParse;
+  sWalker.xExprCallback = renameUnmapExprCb;
+  sWalker.xSelectCallback = renameUnmapSelectCb;
+  pParse->eParseMode = PARSE_MODE_UNMAP;
+  sqlite3WalkExpr(&sWalker, pExpr);
+  pParse->eParseMode = eMode;
+}
+
+/*
+** Remove all nodes that are part of expression-list pEList from the 
+** rename list.
+*/
+void sqlite3RenameExprlistUnmap(Parse *pParse, ExprList *pEList){
+  if( pEList ){
+    int i;
+    Walker sWalker;
+    memset(&sWalker, 0, sizeof(Walker));
+    sWalker.pParse = pParse;
+    sWalker.xExprCallback = renameUnmapExprCb;
+    sqlite3WalkExprList(&sWalker, pEList);
+    for(i=0; i<pEList->nExpr; i++){
+      if( ALWAYS(pEList->a[i].fg.eEName==ENAME_NAME) ){
+        sqlite3RenameTokenRemap(pParse, 0, (void*)pEList->a[i].zEName);
+      }
+    }
+  }
+}
+
+/*
+** Free the list of RenameToken objects given in the second argument
+*/
+static void renameTokenFree(sqlite3 *db, RenameToken *pToken){
+  RenameToken *pNext;
+  RenameToken *p;
+  for(p=pToken; p; p=pNext){
+    pNext = p->pNext;
+    sqlite3DbFree(db, p);
+  }
+}
+
+/*
+** Search the Parse object passed as the first argument for a RenameToken
+** object associated with parse tree element pPtr. If found, return a pointer
+** to it. Otherwise, return NULL.
+**
+** If the second argument passed to this function is not NULL and a matching
+** RenameToken object is found, remove it from the Parse object and add it to
+** the list maintained by the RenameCtx object.
+*/
+static RenameToken *renameTokenFind(
+  Parse *pParse, 
+  struct RenameCtx *pCtx, 
+  const void *pPtr
+){
+  RenameToken **pp;
+  if( NEVER(pPtr==0) ){
+    return 0;
+  }
+  for(pp=&pParse->pRename; (*pp); pp=&(*pp)->pNext){
+    if( (*pp)->p==pPtr ){
+      RenameToken *pToken = *pp;
+      if( pCtx ){
+        *pp = pToken->pNext;
+        pToken->pNext = pCtx->pList;
+        pCtx->pList = pToken;
+        pCtx->nList++;
+      }
+      return pToken;
+    }
+  }
+  return 0;
+}
+
+/*
+** This is a Walker select callback. It does nothing. It is only required
+** because without a dummy callback, sqlite3WalkExpr() and similar do not
+** descend into sub-select statements.
+*/
+static int renameColumnSelectCb(Walker *pWalker, Select *p){
+  if( p->selFlags & (SF_View|SF_CopyCte) ){
+    testcase( p->selFlags & SF_View );
+    testcase( p->selFlags & SF_CopyCte );
+    return WRC_Prune;
+  }
+  renameWalkWith(pWalker, p);
+  return WRC_Continue;
+}
+
+/*
+** This is a Walker expression callback.
+**
+** For every TK_COLUMN node in the expression tree, search to see
+** if the column being references is the column being renamed by an
+** ALTER TABLE statement.  If it is, then attach its associated
+** RenameToken object to the list of RenameToken objects being
+** constructed in RenameCtx object at pWalker->u.pRename.
+*/
+static int renameColumnExprCb(Walker *pWalker, Expr *pExpr){
+  RenameCtx *p = pWalker->u.pRename;
+  if( pExpr->op==TK_TRIGGER 
+   && pExpr->iColumn==p->iCol 
+   && pWalker->pParse->pTriggerTab==p->pTab
+  ){
+    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
+  }else if( pExpr->op==TK_COLUMN 
+   && pExpr->iColumn==p->iCol
+   && ALWAYS(ExprUseYTab(pExpr))
+   && p->pTab==pExpr->y.pTab
+  ){
+    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
+  }
+  return WRC_Continue;
+}
+
+/*
+** The RenameCtx contains a list of tokens that reference a column that
+** is being renamed by an ALTER TABLE statement.  Return the "last"
+** RenameToken in the RenameCtx and remove that RenameToken from the
+** RenameContext.  "Last" means the last RenameToken encountered when
+** the input SQL is parsed from left to right.  Repeated calls to this routine
+** return all column name tokens in the order that they are encountered
+** in the SQL statement.
+*/
+static RenameToken *renameColumnTokenNext(RenameCtx *pCtx){
+  RenameToken *pBest = pCtx->pList;
+  RenameToken *pToken;
+  RenameToken **pp;
+
+  for(pToken=pBest->pNext; pToken; pToken=pToken->pNext){
+    if( pToken->t.z>pBest->t.z ) pBest = pToken;
+  }
+  for(pp=&pCtx->pList; *pp!=pBest; pp=&(*pp)->pNext);
+  *pp = pBest->pNext;
+
+  return pBest;
+}
+
+/*
+** An error occured while parsing or otherwise processing a database
+** object (either pParse->pNewTable, pNewIndex or pNewTrigger) as part of an
+** ALTER TABLE RENAME COLUMN program. The error message emitted by the
+** sub-routine is currently stored in pParse->zErrMsg. This function
+** adds context to the error message and then stores it in pCtx.
+*/
+static void renameColumnParseError(
+  sqlite3_context *pCtx, 
+  const char *zWhen,
+  sqlite3_value *pType,
+  sqlite3_value *pObject,
+  Parse *pParse
+){
+  const char *zT = (const char*)sqlite3_value_text(pType);
+  const char *zN = (const char*)sqlite3_value_text(pObject);
+  char *zErr;
+
+  zErr = sqlite3MPrintf(pParse->db, "error in %s %s%s%s: %s", 
+      zT, zN, (zWhen[0] ? " " : ""), zWhen,
+      pParse->zErrMsg
+  );
+  sqlite3_result_error(pCtx, zErr, -1);
+  sqlite3DbFree(pParse->db, zErr);
+}
+
+/*
+** For each name in the the expression-list pEList (i.e. each
+** pEList->a[i].zName) that matches the string in zOld, extract the 
+** corresponding rename-token from Parse object pParse and add it
+** to the RenameCtx pCtx.
+*/
+static void renameColumnElistNames(
+  Parse *pParse, 
+  RenameCtx *pCtx, 
+  const ExprList *pEList, 
+  const char *zOld
+){
+  if( pEList ){
+    int i;
+    for(i=0; i<pEList->nExpr; i++){
+      const char *zName = pEList->a[i].zEName;
+      if( ALWAYS(pEList->a[i].fg.eEName==ENAME_NAME)
+       && ALWAYS(zName!=0)
+       && 0==sqlite3_stricmp(zName, zOld)
+      ){
+        renameTokenFind(pParse, pCtx, (const void*)zName);
+      }
+    }
+  }
+}
+
+/*
+** For each name in the the id-list pIdList (i.e. each pIdList->a[i].zName) 
+** that matches the string in zOld, extract the corresponding rename-token 
+** from Parse object pParse and add it to the RenameCtx pCtx.
+*/
+static void renameColumnIdlistNames(
+  Parse *pParse, 
+  RenameCtx *pCtx, 
+  const IdList *pIdList, 
+  const char *zOld
+){
+  if( pIdList ){
+    int i;
+    for(i=0; i<pIdList->nId; i++){
+      const char *zName = pIdList->a[i].zName;
+      if( 0==sqlite3_stricmp(zName, zOld) ){
+        renameTokenFind(pParse, pCtx, (const void*)zName);
+      }
+    }
+  }
+}
+
+
+/*
+** Parse the SQL statement zSql using Parse object (*p). The Parse object
+** is initialized by this function before it is used.
+*/
+static int renameParseSql(
+  Parse *p,                       /* Memory to use for Parse object */
+  const char *zDb,                /* Name of schema SQL belongs to */
+  sqlite3 *db,                    /* Database handle */
+  const char *zSql,               /* SQL to parse */
+  int bTemp                       /* True if SQL is from temp schema */
+){
+  int rc;
+
+  sqlite3ParseObjectInit(p, db);
+  if( zSql==0 ){
+    return SQLITE_NOMEM;
+  }
+  if( sqlite3StrNICmp(zSql,"CREATE ",7)!=0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  db->init.iDb = bTemp ? 1 : sqlite3FindDbName(db, zDb);
+  p->eParseMode = PARSE_MODE_RENAME;
+  p->db = db;
+  p->nQueryLoop = 1;
+  rc = sqlite3RunParser(p, zSql);
+  if( db->mallocFailed ) rc = SQLITE_NOMEM;
+  if( rc==SQLITE_OK 
+   && NEVER(p->pNewTable==0 && p->pNewIndex==0 && p->pNewTrigger==0)
+  ){
+    rc = SQLITE_CORRUPT_BKPT;
+  }
+
+#ifdef SQLITE_DEBUG
+  /* Ensure that all mappings in the Parse.pRename list really do map to
+  ** a part of the input string.  */
+  if( rc==SQLITE_OK ){
+    int nSql = sqlite3Strlen30(zSql);
+    RenameToken *pToken;
+    for(pToken=p->pRename; pToken; pToken=pToken->pNext){
+      assert( pToken->t.z>=zSql && &pToken->t.z[pToken->t.n]<=&zSql[nSql] );
+    }
+  }
+#endif
+
+  db->init.iDb = 0;
+  return rc;
+}
+
+/*
+** This function edits SQL statement zSql, replacing each token identified
+** by the linked list pRename with the text of zNew. If argument bQuote is
+** true, then zNew is always quoted first. If no error occurs, the result
+** is loaded into context object pCtx as the result.
+**
+** Or, if an error occurs (i.e. an OOM condition), an error is left in
+** pCtx and an SQLite error code returned.
+*/
+static int renameEditSql(
+  sqlite3_context *pCtx,          /* Return result here */
+  RenameCtx *pRename,             /* Rename context */
+  const char *zSql,               /* SQL statement to edit */
+  const char *zNew,               /* New token text */
+  int bQuote                      /* True to always quote token */
+){
+  i64 nNew = sqlite3Strlen30(zNew);
+  i64 nSql = sqlite3Strlen30(zSql);
+  sqlite3 *db = sqlite3_context_db_handle(pCtx);
+  int rc = SQLITE_OK;
+  char *zQuot = 0;
+  char *zOut;
+  i64 nQuot = 0;
+  char *zBuf1 = 0;
+  char *zBuf2 = 0;
+
+  if( zNew ){
+    /* Set zQuot to point to a buffer containing a quoted copy of the 
+    ** identifier zNew. If the corresponding identifier in the original 
+    ** ALTER TABLE statement was quoted (bQuote==1), then set zNew to
+    ** point to zQuot so that all substitutions are made using the
+    ** quoted version of the new column name.  */
+    zQuot = sqlite3MPrintf(db, "\"%w\" ", zNew);
+    if( zQuot==0 ){
+      return SQLITE_NOMEM;
+    }else{
+      nQuot = sqlite3Strlen30(zQuot)-1;
+    }
+
+    assert( nQuot>=nNew );
+    zOut = sqlite3DbMallocZero(db, nSql + pRename->nList*nQuot + 1);
+  }else{
+    zOut = (char*)sqlite3DbMallocZero(db, (nSql*2+1) * 3);
+    if( zOut ){
+      zBuf1 = &zOut[nSql*2+1];
+      zBuf2 = &zOut[nSql*4+2];
+    }
+  }
+
+  /* At this point pRename->pList contains a list of RenameToken objects
+  ** corresponding to all tokens in the input SQL that must be replaced
+  ** with the new column name, or with single-quoted versions of themselves. 
+  ** All that remains is to construct and return the edited SQL string. */
+  if( zOut ){
+    int nOut = nSql;
+    memcpy(zOut, zSql, nSql);
+    while( pRename->pList ){
+      int iOff;                   /* Offset of token to replace in zOut */
+      u32 nReplace;
+      const char *zReplace;
+      RenameToken *pBest = renameColumnTokenNext(pRename);
+
+      if( zNew ){
+        if( bQuote==0 && sqlite3IsIdChar(*pBest->t.z) ){
+          nReplace = nNew;
+          zReplace = zNew;
+        }else{
+          nReplace = nQuot;
+          zReplace = zQuot;
+          if( pBest->t.z[pBest->t.n]=='"' ) nReplace++;
+        }
+      }else{
+        /* Dequote the double-quoted token. Then requote it again, this time
+        ** using single quotes. If the character immediately following the
+        ** original token within the input SQL was a single quote ('), then
+        ** add another space after the new, single-quoted version of the
+        ** token. This is so that (SELECT "string"'alias') maps to
+        ** (SELECT 'string' 'alias'), and not (SELECT 'string''alias').  */
+        memcpy(zBuf1, pBest->t.z, pBest->t.n);
+        zBuf1[pBest->t.n] = 0;
+        sqlite3Dequote(zBuf1);
+        sqlite3_snprintf(nSql*2, zBuf2, "%Q%s", zBuf1,
+            pBest->t.z[pBest->t.n]=='\'' ? " " : ""
+        );
+        zReplace = zBuf2;
+        nReplace = sqlite3Strlen30(zReplace);
+      }
+
+      iOff = pBest->t.z - zSql;
+      if( pBest->t.n!=nReplace ){
+        memmove(&zOut[iOff + nReplace], &zOut[iOff + pBest->t.n], 
+            nOut - (iOff + pBest->t.n)
+        );
+        nOut += nReplace - pBest->t.n;
+        zOut[nOut] = '\0';
+      }
+      memcpy(&zOut[iOff], zReplace, nReplace);
+      sqlite3DbFree(db, pBest);
+    }
+
+    sqlite3_result_text(pCtx, zOut, -1, SQLITE_TRANSIENT);
+    sqlite3DbFree(db, zOut);
+  }else{
+    rc = SQLITE_NOMEM;
+  }
+
+  sqlite3_free(zQuot);
+  return rc;
+}
+
+/*
+** Resolve all symbols in the trigger at pParse->pNewTrigger, assuming
+** it was read from the schema of database zDb. Return SQLITE_OK if 
+** successful. Otherwise, return an SQLite error code and leave an error
+** message in the Parse object.
+*/
+static int renameResolveTrigger(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  Trigger *pNew = pParse->pNewTrigger;
+  TriggerStep *pStep;
+  NameContext sNC;
+  int rc = SQLITE_OK;
+
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pParse = pParse;
+  assert( pNew->pTabSchema );
+  pParse->pTriggerTab = sqlite3FindTable(db, pNew->table, 
+      db->aDb[sqlite3SchemaToIndex(db, pNew->pTabSchema)].zDbSName
+  );
+  pParse->eTriggerOp = pNew->op;
+  /* ALWAYS() because if the table of the trigger does not exist, the
+  ** error would have been hit before this point */
+  if( ALWAYS(pParse->pTriggerTab) ){
+    rc = sqlite3ViewGetColumnNames(pParse, pParse->pTriggerTab);
+  }
+
+  /* Resolve symbols in WHEN clause */
+  if( rc==SQLITE_OK && pNew->pWhen ){
+    rc = sqlite3ResolveExprNames(&sNC, pNew->pWhen);
+  }
+
+  for(pStep=pNew->step_list; rc==SQLITE_OK && pStep; pStep=pStep->pNext){
+    if( pStep->pSelect ){
+      sqlite3SelectPrep(pParse, pStep->pSelect, &sNC);
+      if( pParse->nErr ) rc = pParse->rc;
+    }
+    if( rc==SQLITE_OK && pStep->zTarget ){
+      SrcList *pSrc = sqlite3TriggerStepSrc(pParse, pStep);
+      if( pSrc ){
+        Select *pSel = sqlite3SelectNew(
+            pParse, pStep->pExprList, pSrc, 0, 0, 0, 0, 0, 0
+        );
+        if( pSel==0 ){
+          pStep->pExprList = 0;
+          pSrc = 0;
+          rc = SQLITE_NOMEM;
+        }else{
+          sqlite3SelectPrep(pParse, pSel, 0);
+          rc = pParse->nErr ? SQLITE_ERROR : SQLITE_OK;
+          assert( pStep->pExprList==0 || pStep->pExprList==pSel->pEList );
+          assert( pSrc==pSel->pSrc );
+          if( pStep->pExprList ) pSel->pEList = 0;
+          pSel->pSrc = 0;
+          sqlite3SelectDelete(db, pSel);
+        }
+        if( pStep->pFrom ){
+          int i;
+          for(i=0; i<pStep->pFrom->nSrc && rc==SQLITE_OK; i++){
+            SrcItem *p = &pStep->pFrom->a[i];
+            if( p->pSelect ){
+              sqlite3SelectPrep(pParse, p->pSelect, 0);
+            }
+          }
+        }
+
+        if(  db->mallocFailed ){
+          rc = SQLITE_NOMEM;
+        }
+        sNC.pSrcList = pSrc;
+        if( rc==SQLITE_OK && pStep->pWhere ){
+          rc = sqlite3ResolveExprNames(&sNC, pStep->pWhere);
+        }
+        if( rc==SQLITE_OK ){
+          rc = sqlite3ResolveExprListNames(&sNC, pStep->pExprList);
+        }
+        assert( !pStep->pUpsert || (!pStep->pWhere && !pStep->pExprList) );
+        if( pStep->pUpsert && rc==SQLITE_OK ){
+          Upsert *pUpsert = pStep->pUpsert;
+          pUpsert->pUpsertSrc = pSrc;
+          sNC.uNC.pUpsert = pUpsert;
+          sNC.ncFlags = NC_UUpsert;
+          rc = sqlite3ResolveExprListNames(&sNC, pUpsert->pUpsertTarget);
+          if( rc==SQLITE_OK ){
+            ExprList *pUpsertSet = pUpsert->pUpsertSet;
+            rc = sqlite3ResolveExprListNames(&sNC, pUpsertSet);
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3ResolveExprNames(&sNC, pUpsert->pUpsertWhere);
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3ResolveExprNames(&sNC, pUpsert->pUpsertTargetWhere);
+          }
+          sNC.ncFlags = 0;
+        }
+        sNC.pSrcList = 0;
+        sqlite3SrcListDelete(db, pSrc);
+      }else{
+        rc = SQLITE_NOMEM;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Invoke sqlite3WalkExpr() or sqlite3WalkSelect() on all Select or Expr
+** objects that are part of the trigger passed as the second argument.
+*/
+static void renameWalkTrigger(Walker *pWalker, Trigger *pTrigger){
+  TriggerStep *pStep;
+
+  /* Find tokens to edit in WHEN clause */
+  sqlite3WalkExpr(pWalker, pTrigger->pWhen);
+
+  /* Find tokens to edit in trigger steps */
+  for(pStep=pTrigger->step_list; pStep; pStep=pStep->pNext){
+    sqlite3WalkSelect(pWalker, pStep->pSelect);
+    sqlite3WalkExpr(pWalker, pStep->pWhere);
+    sqlite3WalkExprList(pWalker, pStep->pExprList);
+    if( pStep->pUpsert ){
+      Upsert *pUpsert = pStep->pUpsert;
+      sqlite3WalkExprList(pWalker, pUpsert->pUpsertTarget);
+      sqlite3WalkExprList(pWalker, pUpsert->pUpsertSet);
+      sqlite3WalkExpr(pWalker, pUpsert->pUpsertWhere);
+      sqlite3WalkExpr(pWalker, pUpsert->pUpsertTargetWhere);
+    }
+    if( pStep->pFrom ){
+      int i;
+      for(i=0; i<pStep->pFrom->nSrc; i++){
+        sqlite3WalkSelect(pWalker, pStep->pFrom->a[i].pSelect);
+      }
+    }
+  }
+}
+
+/*
+** Free the contents of Parse object (*pParse). Do not free the memory
+** occupied by the Parse object itself.
+*/
+static void renameParseCleanup(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  Index *pIdx;
+  if( pParse->pVdbe ){
+    sqlite3VdbeFinalize(pParse->pVdbe);
+  }
+  sqlite3DeleteTable(db, pParse->pNewTable);
+  while( (pIdx = pParse->pNewIndex)!=0 ){
+    pParse->pNewIndex = pIdx->pNext;
+    sqlite3FreeIndex(db, pIdx);
+  }
+  sqlite3DeleteTrigger(db, pParse->pNewTrigger);
+  sqlite3DbFree(db, pParse->zErrMsg);
+  renameTokenFree(db, pParse->pRename);
+  sqlite3ParseObjectReset(pParse);
+}
+
+/*
+** SQL function:
+**
+**     sqlite_rename_column(SQL,TYPE,OBJ,DB,TABLE,COL,NEWNAME,QUOTE,TEMP)
+**
+**   0. zSql:     SQL statement to rewrite
+**   1. type:     Type of object ("table", "view" etc.)
+**   2. object:   Name of object
+**   3. Database: Database name (e.g. "main")
+**   4. Table:    Table name
+**   5. iCol:     Index of column to rename
+**   6. zNew:     New column name
+**   7. bQuote:   Non-zero if the new column name should be quoted.
+**   8. bTemp:    True if zSql comes from temp schema
+**
+** Do a column rename operation on the CREATE statement given in zSql.
+** The iCol-th column (left-most is 0) of table zTable is renamed from zCol
+** into zNew.  The name should be quoted if bQuote is true.
+**
+** This function is used internally by the ALTER TABLE RENAME COLUMN command.
+** It is only accessible to SQL created using sqlite3NestedParse().  It is
+** not reachable from ordinary SQL passed into sqlite3_prepare() unless the
+** SQLITE_TESTCTRL_INTERNAL_FUNCTIONS test setting is enabled.
+*/
+static void renameColumnFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  RenameCtx sCtx;
+  const char *zSql = (const char*)sqlite3_value_text(argv[0]);
+  const char *zDb = (const char*)sqlite3_value_text(argv[3]);
+  const char *zTable = (const char*)sqlite3_value_text(argv[4]);
+  int iCol = sqlite3_value_int(argv[5]);
+  const char *zNew = (const char*)sqlite3_value_text(argv[6]);
+  int bQuote = sqlite3_value_int(argv[7]);
+  int bTemp = sqlite3_value_int(argv[8]);
+  const char *zOld;
+  int rc;
+  Parse sParse;
+  Walker sWalker;
+  Index *pIdx;
+  int i;
+  Table *pTab;
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth = db->xAuth;
+#endif
+
+  UNUSED_PARAMETER(NotUsed);
+  if( zSql==0 ) return;
+  if( zTable==0 ) return;
+  if( zNew==0 ) return;
+  if( iCol<0 ) return;
+  sqlite3BtreeEnterAll(db);
+  pTab = sqlite3FindTable(db, zTable, zDb);
+  if( pTab==0 || iCol>=pTab->nCol ){
+    sqlite3BtreeLeaveAll(db);
+    return;
+  }
+  zOld = pTab->aCol[iCol].zCnName;
+  memset(&sCtx, 0, sizeof(sCtx));
+  sCtx.iCol = ((iCol==pTab->iPKey) ? -1 : iCol);
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  db->xAuth = 0;
+#endif
+  rc = renameParseSql(&sParse, zDb, db, zSql, bTemp);
+
+  /* Find tokens that need to be replaced. */
+  memset(&sWalker, 0, sizeof(Walker));
+  sWalker.pParse = &sParse;
+  sWalker.xExprCallback = renameColumnExprCb;
+  sWalker.xSelectCallback = renameColumnSelectCb;
+  sWalker.u.pRename = &sCtx;
+
+  sCtx.pTab = pTab;
+  if( rc!=SQLITE_OK ) goto renameColumnFunc_done;
+  if( sParse.pNewTable ){
+    if( IsView(sParse.pNewTable) ){
+      Select *pSelect = sParse.pNewTable->u.view.pSelect;
+      pSelect->selFlags &= ~SF_View;
+      sParse.rc = SQLITE_OK;
+      sqlite3SelectPrep(&sParse, pSelect, 0);
+      rc = (db->mallocFailed ? SQLITE_NOMEM : sParse.rc);
+      if( rc==SQLITE_OK ){
+        sqlite3WalkSelect(&sWalker, pSelect);
+      }
+      if( rc!=SQLITE_OK ) goto renameColumnFunc_done;
+    }else if( IsOrdinaryTable(sParse.pNewTable) ){
+      /* A regular table */
+      int bFKOnly = sqlite3_stricmp(zTable, sParse.pNewTable->zName);
+      FKey *pFKey;
+      sCtx.pTab = sParse.pNewTable;
+      if( bFKOnly==0 ){
+        if( iCol<sParse.pNewTable->nCol ){
+          renameTokenFind(
+              &sParse, &sCtx, (void*)sParse.pNewTable->aCol[iCol].zCnName
+          );
+        }
+        if( sCtx.iCol<0 ){
+          renameTokenFind(&sParse, &sCtx, (void*)&sParse.pNewTable->iPKey);
+        }
+        sqlite3WalkExprList(&sWalker, sParse.pNewTable->pCheck);
+        for(pIdx=sParse.pNewTable->pIndex; pIdx; pIdx=pIdx->pNext){
+          sqlite3WalkExprList(&sWalker, pIdx->aColExpr);
+        }
+        for(pIdx=sParse.pNewIndex; pIdx; pIdx=pIdx->pNext){
+          sqlite3WalkExprList(&sWalker, pIdx->aColExpr);
+        }
+#ifndef SQLITE_OMIT_GENERATED_COLUMNS
+        for(i=0; i<sParse.pNewTable->nCol; i++){
+          Expr *pExpr = sqlite3ColumnExpr(sParse.pNewTable,
+                                                  &sParse.pNewTable->aCol[i]);
+          sqlite3WalkExpr(&sWalker, pExpr);
+        }
+#endif
+      }
+
+      assert( IsOrdinaryTable(sParse.pNewTable) );
+      for(pFKey=sParse.pNewTable->u.tab.pFKey; pFKey; pFKey=pFKey->pNextFrom){
+        for(i=0; i<pFKey->nCol; i++){
+          if( bFKOnly==0 && pFKey->aCol[i].iFrom==iCol ){
+            renameTokenFind(&sParse, &sCtx, (void*)&pFKey->aCol[i]);
+          }
+          if( 0==sqlite3_stricmp(pFKey->zTo, zTable)
+           && 0==sqlite3_stricmp(pFKey->aCol[i].zCol, zOld)
+          ){
+            renameTokenFind(&sParse, &sCtx, (void*)pFKey->aCol[i].zCol);
+          }
+        }
+      }
+    }
+  }else if( sParse.pNewIndex ){
+    sqlite3WalkExprList(&sWalker, sParse.pNewIndex->aColExpr);
+    sqlite3WalkExpr(&sWalker, sParse.pNewIndex->pPartIdxWhere);
+  }else{
+    /* A trigger */
+    TriggerStep *pStep;
+    rc = renameResolveTrigger(&sParse);
+    if( rc!=SQLITE_OK ) goto renameColumnFunc_done;
+
+    for(pStep=sParse.pNewTrigger->step_list; pStep; pStep=pStep->pNext){
+      if( pStep->zTarget ){ 
+        Table *pTarget = sqlite3LocateTable(&sParse, 0, pStep->zTarget, zDb);
+        if( pTarget==pTab ){
+          if( pStep->pUpsert ){
+            ExprList *pUpsertSet = pStep->pUpsert->pUpsertSet;
+            renameColumnElistNames(&sParse, &sCtx, pUpsertSet, zOld);
+          }
+          renameColumnIdlistNames(&sParse, &sCtx, pStep->pIdList, zOld);
+          renameColumnElistNames(&sParse, &sCtx, pStep->pExprList, zOld);
+        }
+      }
+    }
+
+
+    /* Find tokens to edit in UPDATE OF clause */
+    if( sParse.pTriggerTab==pTab ){
+      renameColumnIdlistNames(&sParse, &sCtx,sParse.pNewTrigger->pColumns,zOld);
+    }
+
+    /* Find tokens to edit in various expressions and selects */
+    renameWalkTrigger(&sWalker, sParse.pNewTrigger);
+  }
+
+  assert( rc==SQLITE_OK );
+  rc = renameEditSql(context, &sCtx, zSql, zNew, bQuote);
+
+renameColumnFunc_done:
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_ERROR && sqlite3WritableSchema(db) ){
+      sqlite3_result_value(context, argv[0]);
+    }else if( sParse.zErrMsg ){
+      renameColumnParseError(context, "", argv[1], argv[2], &sParse);
+    }else{
+      sqlite3_result_error_code(context, rc);
+    }
+  }
+
+  renameParseCleanup(&sParse);
+  renameTokenFree(db, sCtx.pList);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  db->xAuth = xAuth;
+#endif
+  sqlite3BtreeLeaveAll(db);
+}
+
+/*
+** Walker expression callback used by "RENAME TABLE". 
+*/
+static int renameTableExprCb(Walker *pWalker, Expr *pExpr){
+  RenameCtx *p = pWalker->u.pRename;
+  if( pExpr->op==TK_COLUMN
+   && ALWAYS(ExprUseYTab(pExpr))
+   && p->pTab==pExpr->y.pTab
+  ){
+    renameTokenFind(pWalker->pParse, p, (void*)&pExpr->y.pTab);
+  }
+  return WRC_Continue;
+}
+
+/*
+** Walker select callback used by "RENAME TABLE". 
+*/
+static int renameTableSelectCb(Walker *pWalker, Select *pSelect){
+  int i;
+  RenameCtx *p = pWalker->u.pRename;
+  SrcList *pSrc = pSelect->pSrc;
+  if( pSelect->selFlags & (SF_View|SF_CopyCte) ){
+    testcase( pSelect->selFlags & SF_View );
+    testcase( pSelect->selFlags & SF_CopyCte );
+    return WRC_Prune;
+  }
+  if( NEVER(pSrc==0) ){
+    assert( pWalker->pParse->db->mallocFailed );
+    return WRC_Abort;
+  }
+  for(i=0; i<pSrc->nSrc; i++){
+    SrcItem *pItem = &pSrc->a[i];
+    if( pItem->pTab==p->pTab ){
+      renameTokenFind(pWalker->pParse, p, pItem->zName);
+    }
+  }
+  renameWalkWith(pWalker, pSelect);
+
+  return WRC_Continue;
+}
+
+
+/*
+** This C function implements an SQL user function that is used by SQL code
+** generated by the ALTER TABLE ... RENAME command to modify the definition
+** of any foreign key constraints that use the table being renamed as the 
+** parent table. It is passed three arguments:
+**
+**   0: The database containing the table being renamed.
+**   1. type:     Type of object ("table", "view" etc.)
+**   2. object:   Name of object
+**   3: The complete text of the schema statement being modified,
+**   4: The old name of the table being renamed, and
+**   5: The new name of the table being renamed.
+**   6: True if the schema statement comes from the temp db.
+**
+** It returns the new schema statement. For example:
+**
+** sqlite_rename_table('main', 'CREATE TABLE t1(a REFERENCES t2)','t2','t3',0)
+**       -> 'CREATE TABLE t1(a REFERENCES t3)'
+*/
+static void renameTableFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  const char *zDb = (const char*)sqlite3_value_text(argv[0]);
+  const char *zInput = (const char*)sqlite3_value_text(argv[3]);
+  const char *zOld = (const char*)sqlite3_value_text(argv[4]);
+  const char *zNew = (const char*)sqlite3_value_text(argv[5]);
+  int bTemp = sqlite3_value_int(argv[6]);
+  UNUSED_PARAMETER(NotUsed);
+
+  if( zInput && zOld && zNew ){
+    Parse sParse;
+    int rc;
+    int bQuote = 1;
+    RenameCtx sCtx;
+    Walker sWalker;
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    sqlite3_xauth xAuth = db->xAuth;
+    db->xAuth = 0;
+#endif
+
+    sqlite3BtreeEnterAll(db);
+
+    memset(&sCtx, 0, sizeof(RenameCtx));
+    sCtx.pTab = sqlite3FindTable(db, zOld, zDb);
+    memset(&sWalker, 0, sizeof(Walker));
+    sWalker.pParse = &sParse;
+    sWalker.xExprCallback = renameTableExprCb;
+    sWalker.xSelectCallback = renameTableSelectCb;
+    sWalker.u.pRename = &sCtx;
+
+    rc = renameParseSql(&sParse, zDb, db, zInput, bTemp);
+
+    if( rc==SQLITE_OK ){
+      int isLegacy = (db->flags & SQLITE_LegacyAlter);
+      if( sParse.pNewTable ){
+        Table *pTab = sParse.pNewTable;
+
+        if( IsView(pTab) ){
+          if( isLegacy==0 ){
+            Select *pSelect = pTab->u.view.pSelect;
+            NameContext sNC;
+            memset(&sNC, 0, sizeof(sNC));
+            sNC.pParse = &sParse;
+
+            assert( pSelect->selFlags & SF_View );
+            pSelect->selFlags &= ~SF_View;
+            sqlite3SelectPrep(&sParse, pTab->u.view.pSelect, &sNC);
+            if( sParse.nErr ){
+              rc = sParse.rc;
+            }else{
+              sqlite3WalkSelect(&sWalker, pTab->u.view.pSelect);
+            }
+          }
+        }else{
+          /* Modify any FK definitions to point to the new table. */
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+          if( (isLegacy==0 || (db->flags & SQLITE_ForeignKeys))
+           && !IsVirtual(pTab)
+          ){
+            FKey *pFKey;
+            assert( IsOrdinaryTable(pTab) );
+            for(pFKey=pTab->u.tab.pFKey; pFKey; pFKey=pFKey->pNextFrom){
+              if( sqlite3_stricmp(pFKey->zTo, zOld)==0 ){
+                renameTokenFind(&sParse, &sCtx, (void*)pFKey->zTo);
+              }
+            }
+          }
+#endif
+
+          /* If this is the table being altered, fix any table refs in CHECK
+          ** expressions. Also update the name that appears right after the
+          ** "CREATE [VIRTUAL] TABLE" bit. */
+          if( sqlite3_stricmp(zOld, pTab->zName)==0 ){
+            sCtx.pTab = pTab;
+            if( isLegacy==0 ){
+              sqlite3WalkExprList(&sWalker, pTab->pCheck);
+            }
+            renameTokenFind(&sParse, &sCtx, pTab->zName);
+          }
+        }
+      }
+
+      else if( sParse.pNewIndex ){
+        renameTokenFind(&sParse, &sCtx, sParse.pNewIndex->zName);
+        if( isLegacy==0 ){
+          sqlite3WalkExpr(&sWalker, sParse.pNewIndex->pPartIdxWhere);
+        }
+      }
+
+#ifndef SQLITE_OMIT_TRIGGER
+      else{
+        Trigger *pTrigger = sParse.pNewTrigger;
+        TriggerStep *pStep;
+        if( 0==sqlite3_stricmp(sParse.pNewTrigger->table, zOld) 
+            && sCtx.pTab->pSchema==pTrigger->pTabSchema
+          ){
+          renameTokenFind(&sParse, &sCtx, sParse.pNewTrigger->table);
+        }
+
+        if( isLegacy==0 ){
+          rc = renameResolveTrigger(&sParse);
+          if( rc==SQLITE_OK ){
+            renameWalkTrigger(&sWalker, pTrigger);
+            for(pStep=pTrigger->step_list; pStep; pStep=pStep->pNext){
+              if( pStep->zTarget && 0==sqlite3_stricmp(pStep->zTarget, zOld) ){
+                renameTokenFind(&sParse, &sCtx, pStep->zTarget);
+              }
+              if( pStep->pFrom ){
+                int i;
+                for(i=0; i<pStep->pFrom->nSrc; i++){
+                  SrcItem *pItem = &pStep->pFrom->a[i];
+                  if( 0==sqlite3_stricmp(pItem->zName, zOld) ){
+                    renameTokenFind(&sParse, &sCtx, pItem->zName);
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+#endif
+    }
+
+    if( rc==SQLITE_OK ){
+      rc = renameEditSql(context, &sCtx, zInput, zNew, bQuote);
+    }
+    if( rc!=SQLITE_OK ){
+      if( rc==SQLITE_ERROR && sqlite3WritableSchema(db) ){
+        sqlite3_result_value(context, argv[3]);
+      }else if( sParse.zErrMsg ){
+        renameColumnParseError(context, "", argv[1], argv[2], &sParse);
+      }else{
+        sqlite3_result_error_code(context, rc);
+      }
+    }
+
+    renameParseCleanup(&sParse);
+    renameTokenFree(db, sCtx.pList);
+    sqlite3BtreeLeaveAll(db);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    db->xAuth = xAuth;
+#endif
+  }
+
+  return;
+}
+
+static int renameQuotefixExprCb(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_STRING && (pExpr->flags & EP_DblQuoted) ){
+    renameTokenFind(pWalker->pParse, pWalker->u.pRename, (const void*)pExpr);
+  }
+  return WRC_Continue;
+}
+
+/* SQL function: sqlite_rename_quotefix(DB,SQL)
+**
+** Rewrite the DDL statement "SQL" so that any string literals that use
+** double-quotes use single quotes instead.
+**
+** Two arguments must be passed:
+**
+**   0: Database name ("main", "temp" etc.).
+**   1: SQL statement to edit.
+**
+** The returned value is the modified SQL statement. For example, given
+** the database schema:
+**
+**   CREATE TABLE t1(a, b, c);
+**
+**   SELECT sqlite_rename_quotefix('main', 
+**       'CREATE VIEW v1 AS SELECT "a", "string" FROM t1'
+**   );
+**
+** returns the string:
+** 
+**   CREATE VIEW v1 AS SELECT "a", 'string' FROM t1
+**
+** If there is a error in the input SQL, then raise an error, except
+** if PRAGMA writable_schema=ON, then just return the input string
+** unmodified following an error.
+*/
+static void renameQuotefixFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  char const *zDb = (const char*)sqlite3_value_text(argv[0]);
+  char const *zInput = (const char*)sqlite3_value_text(argv[1]);
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth = db->xAuth;
+  db->xAuth = 0;
+#endif
+
+  sqlite3BtreeEnterAll(db);
+
+  UNUSED_PARAMETER(NotUsed);
+  if( zDb && zInput ){
+    int rc;
+    Parse sParse;
+    rc = renameParseSql(&sParse, zDb, db, zInput, 0);
+
+    if( rc==SQLITE_OK ){
+      RenameCtx sCtx;
+      Walker sWalker;
+
+      /* Walker to find tokens that need to be replaced. */
+      memset(&sCtx, 0, sizeof(RenameCtx));
+      memset(&sWalker, 0, sizeof(Walker));
+      sWalker.pParse = &sParse;
+      sWalker.xExprCallback = renameQuotefixExprCb;
+      sWalker.xSelectCallback = renameColumnSelectCb;
+      sWalker.u.pRename = &sCtx;
+
+      if( sParse.pNewTable ){
+        if( IsView(sParse.pNewTable) ){
+          Select *pSelect = sParse.pNewTable->u.view.pSelect;
+          pSelect->selFlags &= ~SF_View;
+          sParse.rc = SQLITE_OK;
+          sqlite3SelectPrep(&sParse, pSelect, 0);
+          rc = (db->mallocFailed ? SQLITE_NOMEM : sParse.rc);
+          if( rc==SQLITE_OK ){
+            sqlite3WalkSelect(&sWalker, pSelect);
+          }
+        }else{
+          int i;
+          sqlite3WalkExprList(&sWalker, sParse.pNewTable->pCheck);
+#ifndef SQLITE_OMIT_GENERATED_COLUMNS
+          for(i=0; i<sParse.pNewTable->nCol; i++){
+            sqlite3WalkExpr(&sWalker, 
+               sqlite3ColumnExpr(sParse.pNewTable, 
+                                         &sParse.pNewTable->aCol[i]));
+          }
+#endif /* SQLITE_OMIT_GENERATED_COLUMNS */
+        }
+      }else if( sParse.pNewIndex ){
+        sqlite3WalkExprList(&sWalker, sParse.pNewIndex->aColExpr);
+        sqlite3WalkExpr(&sWalker, sParse.pNewIndex->pPartIdxWhere);
+      }else{
+#ifndef SQLITE_OMIT_TRIGGER
+        rc = renameResolveTrigger(&sParse);
+        if( rc==SQLITE_OK ){
+          renameWalkTrigger(&sWalker, sParse.pNewTrigger);
+        }
+#endif /* SQLITE_OMIT_TRIGGER */
+      }
+
+      if( rc==SQLITE_OK ){ 
+        rc = renameEditSql(context, &sCtx, zInput, 0, 0);
+      }
+      renameTokenFree(db, sCtx.pList);
+    }
+    if( rc!=SQLITE_OK ){
+      if( sqlite3WritableSchema(db) && rc==SQLITE_ERROR ){
+        sqlite3_result_value(context, argv[1]);
+      }else{
+        sqlite3_result_error_code(context, rc);
+      }
+    }
+    renameParseCleanup(&sParse);
+  }
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  db->xAuth = xAuth;
+#endif
+
+  sqlite3BtreeLeaveAll(db);
+}
+
+/* Function:  sqlite_rename_test(DB,SQL,TYPE,NAME,ISTEMP,WHEN,DQS)
+**
+** An SQL user function that checks that there are no parse or symbol
+** resolution problems in a CREATE TRIGGER|TABLE|VIEW|INDEX statement.
+** After an ALTER TABLE .. RENAME operation is performed and the schema
+** reloaded, this function is called on each SQL statement in the schema
+** to ensure that it is still usable.
+**
+**   0: Database name ("main", "temp" etc.).
+**   1: SQL statement.
+**   2: Object type ("view", "table", "trigger" or "index").
+**   3: Object name.
+**   4: True if object is from temp schema.
+**   5: "when" part of error message.
+**   6: True to disable the DQS quirk when parsing SQL.
+**
+** The return value is computed as follows:
+**
+**   A. If an error is seen and not in PRAGMA writable_schema=ON mode,
+**      then raise the error.
+**   B. Else if a trigger is created and the the table that the trigger is
+**      attached to is in database zDb, then return 1.
+**   C. Otherwise return NULL.
+*/
+static void renameTableTest(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  char const *zDb = (const char*)sqlite3_value_text(argv[0]);
+  char const *zInput = (const char*)sqlite3_value_text(argv[1]);
+  int bTemp = sqlite3_value_int(argv[4]);
+  int isLegacy = (db->flags & SQLITE_LegacyAlter);
+  char const *zWhen = (const char*)sqlite3_value_text(argv[5]);
+  int bNoDQS = sqlite3_value_int(argv[6]);
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth = db->xAuth;
+  db->xAuth = 0;
+#endif
+
+  UNUSED_PARAMETER(NotUsed);
+
+  if( zDb && zInput ){
+    int rc;
+    Parse sParse;
+    int flags = db->flags;
+    if( bNoDQS ) db->flags &= ~(SQLITE_DqsDML|SQLITE_DqsDDL);
+    rc = renameParseSql(&sParse, zDb, db, zInput, bTemp);
+    db->flags |= (flags & (SQLITE_DqsDML|SQLITE_DqsDDL));
+    if( rc==SQLITE_OK ){
+      if( isLegacy==0 && sParse.pNewTable && IsView(sParse.pNewTable) ){
+        NameContext sNC;
+        memset(&sNC, 0, sizeof(sNC));
+        sNC.pParse = &sParse;
+        sqlite3SelectPrep(&sParse, sParse.pNewTable->u.view.pSelect, &sNC);
+        if( sParse.nErr ) rc = sParse.rc;
+      }
+
+      else if( sParse.pNewTrigger ){
+        if( isLegacy==0 ){
+          rc = renameResolveTrigger(&sParse);
+        }
+        if( rc==SQLITE_OK ){
+          int i1 = sqlite3SchemaToIndex(db, sParse.pNewTrigger->pTabSchema);
+          int i2 = sqlite3FindDbName(db, zDb);
+          if( i1==i2 ){
+            /* Handle output case B */
+            sqlite3_result_int(context, 1);
+          }
+        }
+      }
+    }
+
+    if( rc!=SQLITE_OK && zWhen && !sqlite3WritableSchema(db) ){
+      /* Output case A */
+      renameColumnParseError(context, zWhen, argv[2], argv[3],&sParse);
+    }
+    renameParseCleanup(&sParse);
+  }
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  db->xAuth = xAuth;
+#endif
+}
+
+/*
+** The implementation of internal UDF sqlite_drop_column().
+** 
+** Arguments:
+**
+**  argv[0]: An integer - the index of the schema containing the table
+**  argv[1]: CREATE TABLE statement to modify.
+**  argv[2]: An integer - the index of the column to remove.
+**
+** The value returned is a string containing the CREATE TABLE statement
+** with column argv[2] removed.
+*/
+static void dropColumnFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  int iSchema = sqlite3_value_int(argv[0]);
+  const char *zSql = (const char*)sqlite3_value_text(argv[1]);
+  int iCol = sqlite3_value_int(argv[2]);
+  const char *zDb = db->aDb[iSchema].zDbSName;
+  int rc;
+  Parse sParse;
+  RenameToken *pCol;
+  Table *pTab;
+  const char *zEnd;
+  char *zNew = 0;
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth = db->xAuth;
+  db->xAuth = 0;
+#endif
+
+  UNUSED_PARAMETER(NotUsed);
+  rc = renameParseSql(&sParse, zDb, db, zSql, iSchema==1);
+  if( rc!=SQLITE_OK ) goto drop_column_done;
+  pTab = sParse.pNewTable;
+  if( pTab==0 || pTab->nCol==1 || iCol>=pTab->nCol ){ 
+    /* This can happen if the sqlite_schema table is corrupt */
+    rc = SQLITE_CORRUPT_BKPT;
+    goto drop_column_done;
+  }
+
+  pCol = renameTokenFind(&sParse, 0, (void*)pTab->aCol[iCol].zCnName);
+  if( iCol<pTab->nCol-1 ){
+    RenameToken *pEnd;
+    pEnd = renameTokenFind(&sParse, 0, (void*)pTab->aCol[iCol+1].zCnName);
+    zEnd = (const char*)pEnd->t.z;
+  }else{
+    assert( IsOrdinaryTable(pTab) );
+    zEnd = (const char*)&zSql[pTab->u.tab.addColOffset];
+    while( ALWAYS(pCol->t.z[0]!=0) && pCol->t.z[0]!=',' ) pCol->t.z--;
+  }
+
+  zNew = sqlite3MPrintf(db, "%.*s%s", pCol->t.z-zSql, zSql, zEnd);
+  sqlite3_result_text(context, zNew, -1, SQLITE_TRANSIENT);
+  sqlite3_free(zNew);
+
+drop_column_done:
+  renameParseCleanup(&sParse);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  db->xAuth = xAuth;
+#endif
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(context, rc);
+  }
+}
+
+/*
+** This function is called by the parser upon parsing an 
+**
+**     ALTER TABLE pSrc DROP COLUMN pName
+**
+** statement. Argument pSrc contains the possibly qualified name of the
+** table being edited, and token pName the name of the column to drop.
+*/
+void sqlite3AlterDropColumn(Parse *pParse, SrcList *pSrc, const Token *pName){
+  sqlite3 *db = pParse->db;       /* Database handle */
+  Table *pTab;                    /* Table to modify */
+  int iDb;                        /* Index of db containing pTab in aDb[] */
+  const char *zDb;                /* Database containing pTab ("main" etc.) */
+  char *zCol = 0;                 /* Name of column to drop */
+  int iCol;                       /* Index of column zCol in pTab->aCol[] */
+
+  /* Look up the table being altered. */
+  assert( pParse->pNewTable==0 );
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  if( NEVER(db->mallocFailed) ) goto exit_drop_column;
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_drop_column;
+
+  /* Make sure this is not an attempt to ALTER a view, virtual table or 
+  ** system table. */
+  if( SQLITE_OK!=isAlterableTable(pParse, pTab) ) goto exit_drop_column;
+  if( SQLITE_OK!=isRealTable(pParse, pTab, 1) ) goto exit_drop_column;
+
+  /* Find the index of the column being dropped. */
+  zCol = sqlite3NameFromToken(db, pName);
+  if( zCol==0 ){
+    assert( db->mallocFailed );
+    goto exit_drop_column;
+  }
+  iCol = sqlite3ColumnIndex(pTab, zCol);
+  if( iCol<0 ){
+    sqlite3ErrorMsg(pParse, "no such column: \"%T\"", pName);
+    goto exit_drop_column;
+  }
+
+  /* Do not allow the user to drop a PRIMARY KEY column or a column 
+  ** constrained by a UNIQUE constraint.  */
+  if( pTab->aCol[iCol].colFlags & (COLFLAG_PRIMKEY|COLFLAG_UNIQUE) ){
+    sqlite3ErrorMsg(pParse, "cannot drop %s column: \"%s\"", 
+        (pTab->aCol[iCol].colFlags&COLFLAG_PRIMKEY) ? "PRIMARY KEY" : "UNIQUE",
+        zCol
+    );
+    goto exit_drop_column;
+  }
+
+  /* Do not allow the number of columns to go to zero */
+  if( pTab->nCol<=1 ){
+    sqlite3ErrorMsg(pParse, "cannot drop column \"%s\": no other columns exist",zCol);
+    goto exit_drop_column;
+  }
+
+  /* Edit the sqlite_schema table */
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb>=0 );
+  zDb = db->aDb[iDb].zDbSName;
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, zCol) ){
+    goto exit_drop_column;
+  }
+#endif
+  renameTestSchema(pParse, zDb, iDb==1, "", 0);
+  renameFixQuotes(pParse, zDb, iDb==1);
+  sqlite3NestedParse(pParse, 
+      "UPDATE \"%w\"." LEGACY_SCHEMA_TABLE " SET "
+      "sql = sqlite_drop_column(%d, sql, %d) "
+      "WHERE (type=='table' AND tbl_name=%Q COLLATE nocase)"
+      , zDb, iDb, iCol, pTab->zName
+  );
+
+  /* Drop and reload the database schema. */
+  renameReloadSchema(pParse, iDb, INITFLAG_AlterDrop);
+  renameTestSchema(pParse, zDb, iDb==1, "after drop column", 1);
+
+  /* Edit rows of table on disk */
+  if( pParse->nErr==0 && (pTab->aCol[iCol].colFlags & COLFLAG_VIRTUAL)==0 ){
+    int i;
+    int addr;
+    int reg;
+    int regRec;
+    Index *pPk = 0;
+    int nField = 0;               /* Number of non-virtual columns after drop */
+    int iCur;
+    Vdbe *v = sqlite3GetVdbe(pParse);
+    iCur = pParse->nTab++;
+    sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite);
+    addr = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v);
+    reg = ++pParse->nMem;
+    if( HasRowid(pTab) ){
+      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, reg);
+      pParse->nMem += pTab->nCol;
+    }else{
+      pPk = sqlite3PrimaryKeyIndex(pTab);
+      pParse->nMem += pPk->nColumn;
+      for(i=0; i<pPk->nKeyCol; i++){
+        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, reg+i+1);
+      }
+      nField = pPk->nKeyCol;
+    }
+    regRec = ++pParse->nMem;
+    for(i=0; i<pTab->nCol; i++){
+      if( i!=iCol && (pTab->aCol[i].colFlags & COLFLAG_VIRTUAL)==0 ){
+        int regOut;
+        if( pPk ){
+          int iPos = sqlite3TableColumnToIndex(pPk, i);
+          int iColPos = sqlite3TableColumnToIndex(pPk, iCol);
+          if( iPos<pPk->nKeyCol ) continue;
+          regOut = reg+1+iPos-(iPos>iColPos);
+        }else{
+          regOut = reg+1+nField;
+        }
+        if( i==pTab->iPKey ){
+          sqlite3VdbeAddOp2(v, OP_Null, 0, regOut);
+        }else{
+          sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOut);
+        }
+        nField++;
+      }
+    }
+    if( nField==0 ){
+      /* dbsqlfuzz 5f09e7bcc78b4954d06bf9f2400d7715f48d1fef */
+      pParse->nMem++;
+      sqlite3VdbeAddOp2(v, OP_Null, 0, reg+1);
+      nField = 1;
+    }
+    sqlite3VdbeAddOp3(v, OP_MakeRecord, reg+1, nField, regRec);
+    if( pPk ){
+      sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iCur, regRec, reg+1, pPk->nKeyCol);
+    }else{
+      sqlite3VdbeAddOp3(v, OP_Insert, iCur, regRec, reg);
+    }
+    sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
+
+    sqlite3VdbeAddOp2(v, OP_Next, iCur, addr+1); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addr);
+  }
+
+exit_drop_column:
+  sqlite3DbFree(db, zCol);
+  sqlite3SrcListDelete(db, pSrc);
+}
+
+/*
+** Register built-in functions used to help implement ALTER TABLE
+*/
+void sqlite3AlterFunctions(void){
+  static FuncDef aAlterTableFuncs[] = {
+    INTERNAL_FUNCTION(sqlite_rename_column,  9, renameColumnFunc),
+    INTERNAL_FUNCTION(sqlite_rename_table,   7, renameTableFunc),
+    INTERNAL_FUNCTION(sqlite_rename_test,    7, renameTableTest),
+    INTERNAL_FUNCTION(sqlite_drop_column,    3, dropColumnFunc),
+    INTERNAL_FUNCTION(sqlite_rename_quotefix,2, renameQuotefixFunc),
+  };
+  sqlite3InsertBuiltinFuncs(aAlterTableFuncs, ArraySize(aAlterTableFuncs));
+}
+#endif  /* SQLITE_ALTER_TABLE */