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<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
<h2>Extract Metadata About A Column Of A Table</h2>
</div>
<blockquote><pre>
int sqlite3_table_column_metadata(
sqlite3 *db, /* Connection handle */
const char *zDbName, /* Database name or NULL */
const char *zTableName, /* Table name */
const char *zColumnName, /* Column name */
char const **pzDataType, /* OUTPUT: Declared data type */
char const **pzCollSeq, /* OUTPUT: Collation sequence name */
int *pNotNull, /* OUTPUT: True if NOT NULL constraint exists */
int *pPrimaryKey, /* OUTPUT: True if column part of PK */
int *pAutoinc /* OUTPUT: True if column is auto-increment */
);
</pre></blockquote>
<p>
The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
information about column C of table T in database D
on <a href="../c3ref/sqlite3.html">database connection</a> X. The sqlite3_table_column_metadata()
interface returns SQLITE_OK and fills in the non-NULL pointers in
the final five arguments with appropriate values if the specified
column exists. The sqlite3_table_column_metadata() interface returns
SQLITE_ERROR if the specified column does not exist.
If the column-name parameter to sqlite3_table_column_metadata() is a
NULL pointer, then this routine simply checks for the existence of the
table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
does not. If the table name parameter T in a call to
sqlite3_table_column_metadata(X,D,T,C,...) is NULL then the result is
undefined behavior.</p>
<p>The column is identified by the second, third and fourth parameters to
this function. The second parameter is either the name of the database
(i.e. "main", "temp", or an attached database) containing the specified
table or NULL. If it is NULL, then all attached databases are searched
for the table using the same algorithm used by the database engine to
resolve unqualified table references.</p>
<p>The third and fourth parameters to this function are the table and column
name of the desired column, respectively.</p>
<p>Metadata is returned by writing to the memory locations passed as the 5th
and subsequent parameters to this function. Any of these arguments may be
NULL, in which case the corresponding element of metadata is omitted.</p>
<p><blockquote>
<table border="1">
<tr><th> Parameter <th> Output<br>Type <th> Description</p>
<p><tr><td> 5th <td> const char* <td> Data type
<tr><td> 6th <td> const char* <td> Name of default collation sequence
<tr><td> 7th <td> int <td> True if column has a NOT NULL constraint
<tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY
<tr><td> 9th <td> int <td> True if column is <a href="../autoinc.html">AUTOINCREMENT</a>
</table>
</blockquote></p>
<p>The memory pointed to by the character pointers returned for the
declaration type and collation sequence is valid until the next
call to any SQLite API function.</p>
<p>If the specified table is actually a view, an <a href="../rescode.html">error code</a> is returned.</p>
<p>If the specified column is "rowid", "oid" or "_rowid_" and the table
is not a <a href="../withoutrowid.html">WITHOUT ROWID</a> table and an
<a href="../lang_createtable.html#rowid">INTEGER PRIMARY KEY</a> column has been explicitly declared, then the output
parameters are set for the explicitly declared column. If there is no
<a href="../lang_createtable.html#rowid">INTEGER PRIMARY KEY</a> column, then the outputs
for the <a href="../lang_createtable.html#rowid">rowid</a> are set as follows:</p>
<p><pre>
data type: "INTEGER"
collation sequence: "BINARY"
not null: 0
primary key: 1
auto increment: 0
</pre></p>
<p>This function causes all database schemas to be read from disk and
parsed, if that has not already been done, and returns an error if
any errors are encountered while loading the schema.
</p><p>See also lists of
<a href="../c3ref/objlist.html">Objects</a>,
<a href="../c3ref/constlist.html">Constants</a>, and
<a href="../c3ref/funclist.html">Functions</a>.</p>
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