Adding upstream version 3.45.1.upstream/3.45.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
author: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-13 14:07:11 +0000
committer: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-13 14:07:11 +0000
commit: 63847496f14c813a5d80efd5b7de0f1294ffe1e3 (patch)
tree: 01c7571c7c762ceee70638549a99834fdd7c411b /www/c3ref/preupdate_blobwrite.html
parent: Initial commit. (diff)
download: sqlite3-63847496f14c813a5d80efd5b7de0f1294ffe1e3.tar.xz
sqlite3-63847496f14c813a5d80efd5b7de0f1294ffe1e3.zip
1 files changed, 241 insertions, 0 deletions
diff --git a/www/c3ref/preupdate_blobwrite.html b/www/c3ref/preupdate_blobwrite.html
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+<!DOCTYPE html>
+<html><head>
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<link href="../sqlite.css" rel="stylesheet">
+<title>The pre-update hook.</title>
+<!-- path=../ -->
+</head>
+<body>
+<div class=nosearch>
+<a href="../index.html">
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+<!-- keywords: sqlite3_preupdate_blobwrite sqlite3_preupdate_count sqlite3_preupdate_depth sqlite3_preupdate_hook sqlite3_preupdate_new sqlite3_preupdate_old -->
+<div class=nosearch>
+<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
+<h2>The pre-update hook.</h2>
+</div>
+<blockquote><pre>
+#if defined(SQLITE_ENABLE_PREUPDATE_HOOK)
+void *sqlite3_preupdate_hook(
+  sqlite3 *db,
+  void(*xPreUpdate)(
+    void *pCtx,                   /* Copy of third arg to preupdate_hook() */
+    sqlite3 *db,                  /* Database handle */
+    int op,                       /* SQLITE_UPDATE, DELETE or INSERT */
+    char const *zDb,              /* Database name */
+    char const *zName,            /* Table name */
+    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
+    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
+  ),
+  void*
+);
+int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
+int sqlite3_preupdate_count(sqlite3 *);
+int sqlite3_preupdate_depth(sqlite3 *);
+int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);
+int sqlite3_preupdate_blobwrite(sqlite3 *);
+#endif
+</pre></blockquote>
+<p>
+These interfaces are only available if SQLite is compiled using the
+<a href="../compile.html#enable_preupdate_hook">SQLITE_ENABLE_PREUPDATE_HOOK</a> compile-time option.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_hook()</a> interface registers a callback function
+that is invoked prior to each <a href="../lang_insert.html">INSERT</a>, <a href="../lang_update.html">UPDATE</a>, and <a href="../lang_delete.html">DELETE</a> operation
+on a database table.
+At most one preupdate hook may be registered at a time on a single
+<a href="../c3ref/sqlite3.html">database connection</a>; each call to <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_hook()</a> overrides
+the previous setting.
+The preupdate hook is disabled by invoking <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_hook()</a>
+with a NULL pointer as the second parameter.
+The third parameter to <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_hook()</a> is passed through as
+the first parameter to callbacks.</p>
+
+<p>The preupdate hook only fires for changes to real database tables; the
+preupdate hook is not invoked for changes to <a href="../vtab.html">virtual tables</a> or to
+system tables like sqlite_sequence or sqlite_stat1.</p>
+
+<p>The second parameter to the preupdate callback is a pointer to
+the <a href="../c3ref/sqlite3.html">database connection</a> that registered the preupdate hook.
+The third parameter to the preupdate callback is one of the constants
+<a href="../c3ref/c_alter_table.html">SQLITE_INSERT</a>, <a href="../c3ref/c_alter_table.html">SQLITE_DELETE</a>, or <a href="../c3ref/c_alter_table.html">SQLITE_UPDATE</a> to identify the
+kind of update operation that is about to occur.
+The fourth parameter to the preupdate callback is the name of the
+database within the database connection that is being modified.  This
+will be "main" for the main database or "temp" for TEMP tables or
+the name given after the AS keyword in the <a href="../lang_attach.html">ATTACH</a> statement for attached
+databases.
+The fifth parameter to the preupdate callback is the name of the
+table that is being modified.</p>
+
+<p>For an UPDATE or DELETE operation on a <a href="../rowidtable.html">rowid table</a>, the sixth
+parameter passed to the preupdate callback is the initial <a href="../lang_createtable.html#rowid">rowid</a> of the
+row being modified or deleted. For an INSERT operation on a rowid table,
+or any operation on a WITHOUT ROWID table, the value of the sixth
+parameter is undefined. For an INSERT or UPDATE on a rowid table the
+seventh parameter is the final rowid value of the row being inserted
+or updated. The value of the seventh parameter passed to the callback
+function is not defined for operations on WITHOUT ROWID tables, or for
+DELETE operations on rowid tables.</p>
+
+<p>The sqlite3_preupdate_hook(D,C,P) function returns the P argument from
+the previous call on the same <a href="../c3ref/sqlite3.html">database connection</a> D, or NULL for
+the first call on D.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_old()</a>, <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_new()</a>,
+<a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_count()</a>, and <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_depth()</a> interfaces
+provide additional information about a preupdate event. These routines
+may only be called from within a preupdate callback.  Invoking any of
+these routines from outside of a preupdate callback or with a
+<a href="../c3ref/sqlite3.html">database connection</a> pointer that is different from the one supplied
+to the preupdate callback results in undefined and probably undesirable
+behavior.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_count(D)</a> interface returns the number of columns
+in the row that is being inserted, updated, or deleted.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_old(D,N,P)</a> interface writes into P a pointer to
+a <a href="../c3ref/value.html">protected sqlite3_value</a> that contains the value of the Nth column of
+the table row before it is updated.  The N parameter must be between 0
+and one less than the number of columns or the behavior will be
+undefined. This must only be used within SQLITE_UPDATE and SQLITE_DELETE
+preupdate callbacks; if it is used by an SQLITE_INSERT callback then the
+behavior is undefined.  The <a href="../c3ref/value.html">sqlite3_value</a> that P points to
+will be destroyed when the preupdate callback returns.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_new(D,N,P)</a> interface writes into P a pointer to
+a <a href="../c3ref/value.html">protected sqlite3_value</a> that contains the value of the Nth column of
+the table row after it is updated.  The N parameter must be between 0
+and one less than the number of columns or the behavior will be
+undefined. This must only be used within SQLITE_INSERT and SQLITE_UPDATE
+preupdate callbacks; if it is used by an SQLITE_DELETE callback then the
+behavior is undefined.  The <a href="../c3ref/value.html">sqlite3_value</a> that P points to
+will be destroyed when the preupdate callback returns.</p>
+
+<p>The <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_depth(D)</a> interface returns 0 if the preupdate
+callback was invoked as a result of a direct insert, update, or delete
+operation; or 1 for inserts, updates, or deletes invoked by top-level
+triggers; or 2 for changes resulting from triggers called by top-level
+triggers; and so forth.</p>
+
+<p>When the <a href="../c3ref/blob_write.html">sqlite3_blob_write()</a> API is used to update a blob column,
+the pre-update hook is invoked with SQLITE_DELETE. This is because the
+in this case the new values are not available. In this case, when a
+callback made with op==SQLITE_DELETE is actually a write using the
+sqlite3_blob_write() API, the <a href="../c3ref/preupdate_blobwrite.html">sqlite3_preupdate_blobwrite()</a> returns
+the index of the column being written. In other cases, where the
+pre-update hook is being invoked for some other reason, including a
+regular DELETE, sqlite3_preupdate_blobwrite() returns -1.</p>
+
+<p>See also:  <a href="../c3ref/update_hook.html">sqlite3_update_hook()</a>
+</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>
+
author	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-13 14:07:11 +0000
committer	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-13 14:07:11 +0000
commit	63847496f14c813a5d80efd5b7de0f1294ffe1e3 (patch)
tree	01c7571c7c762ceee70638549a99834fdd7c411b /www/c3ref/preupdate_blobwrite.html
parent	Initial commit. (diff)
download	sqlite3-63847496f14c813a5d80efd5b7de0f1294ffe1e3.tar.xz sqlite3-63847496f14c813a5d80efd5b7de0f1294ffe1e3.zip