Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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Aggiunta documentazione di sqlite 3
2020-11-29 00:32:36 +01:00

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<title>Last Insert Rowid</title>
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>Last Insert Rowid</h2>
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<blockquote><pre>
sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
</pre></blockquote>
<p>
Each entry in most SQLite tables (except for <a href="../withoutrowid.html">WITHOUT ROWID</a> tables)
has a unique 64-bit signed
integer key called the <a href="../lang_createtable.html#rowid">"rowid"</a>. The rowid is always available
as an undeclared column named ROWID, OID, or _ROWID_ as long as those
names are not also used by explicitly declared columns. If
the table has a column of type <a href="../lang_createtable.html#rowid">INTEGER PRIMARY KEY</a> then that column
is another alias for the rowid.</p>
<p>The sqlite3_last_insert_rowid(D) interface usually returns the <a href="../lang_createtable.html#rowid">rowid</a> of
the most recent successful <a href="../lang_insert.html">INSERT</a> into a rowid table or <a href="../vtab.html">virtual table</a>
on database connection D. Inserts into <a href="../withoutrowid.html">WITHOUT ROWID</a> tables are not
recorded. If no successful <a href="../lang_insert.html">INSERT</a>s into rowid tables have ever occurred
on the database connection D, then sqlite3_last_insert_rowid(D) returns
zero.</p>
<p>As well as being set automatically as rows are inserted into database
tables, the value returned by this function may be set explicitly by
<a href="../c3ref/set_last_insert_rowid.html">sqlite3_set_last_insert_rowid()</a></p>
<p>Some virtual table implementations may INSERT rows into rowid tables as
part of committing a transaction (e.g. to flush data accumulated in memory
to disk). In this case subsequent calls to this function return the rowid
associated with these internal INSERT operations, which leads to
unintuitive results. Virtual table implementations that do write to rowid
tables in this way can avoid this problem by restoring the original
rowid value using <a href="../c3ref/set_last_insert_rowid.html">sqlite3_set_last_insert_rowid()</a> before returning
control to the user.</p>
<p>If an <a href="../lang_insert.html">INSERT</a> occurs within a trigger then this routine will
return the <a href="../lang_createtable.html#rowid">rowid</a> of the inserted row as long as the trigger is
running. Once the trigger program ends, the value returned
by this routine reverts to what it was before the trigger was fired.</p>
<p>An <a href="../lang_insert.html">INSERT</a> that fails due to a constraint violation is not a
successful <a href="../lang_insert.html">INSERT</a> and does not change the value returned by this
routine. Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
and INSERT OR ABORT make no changes to the return value of this
routine when their insertion fails. When INSERT OR REPLACE
encounters a constraint violation, it does not fail. The
INSERT continues to completion after deleting rows that caused
the constraint problem so INSERT OR REPLACE will always change
the return value of this interface.</p>
<p>For the purposes of this routine, an <a href="../lang_insert.html">INSERT</a> is considered to
be successful even if it is subsequently rolled back.</p>
<p>This function is accessible to SQL statements via the
<a href="../lang_corefunc.html#last_insert_rowid">last_insert_rowid() SQL function</a>.</p>
<p>If a separate thread performs a new <a href="../lang_insert.html">INSERT</a> on the same
database connection while the <a href="../c3ref/last_insert_rowid.html">sqlite3_last_insert_rowid()</a>
function is running and thus changes the last insert <a href="../lang_createtable.html#rowid">rowid</a>,
then the value returned by <a href="../c3ref/last_insert_rowid.html">sqlite3_last_insert_rowid()</a> is
unpredictable and might not equal either the old or the new
last insert <a href="../lang_createtable.html#rowid">rowid</a>.
</p><p>See also lists of
<a href="objlist.html">Objects</a>,
<a href="constlist.html">Constants</a>, and
<a href="funclist.html">Functions</a>.</p>