campo-sirio/libraries/SQLite3/sqlite-doc-3330000/session/sqlite3changeset_invert.html
Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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<a href="intro.html"><h2>Session Module C Interface</h2></a><h2>Invert A Changeset</h2><blockquote><pre>int sqlite3changeset_invert(
int nIn, const void *pIn, /* Input changeset */
int *pnOut, void **ppOut /* OUT: Inverse of input */
);
</pre></blockquote><p>
This function is used to "invert" a changeset object. Applying an inverted
changeset to a database reverses the effects of applying the uninverted
changeset. Specifically:</p>
<p><ul>
<li> Each DELETE change is changed to an INSERT, and
<li> Each INSERT change is changed to a DELETE, and
<li> For each UPDATE change, the old.* and new.* values are exchanged.
</ul></p>
<p>This function does not change the order in which changes appear within
the changeset. It merely reverses the sense of each individual change.</p>
<p>If successful, a pointer to a buffer containing the inverted changeset
is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
zeroed and an SQLite error code returned.</p>
<p>It is the responsibility of the caller to eventually call sqlite3_free()
on the *ppOut pointer to free the buffer allocation following a successful
call to this function.</p>
<p>WARNING/TODO: This function currently assumes that the input is a valid
changeset. If it is not, the results are undefined.
</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>