SQLite

** no changes will be recorded in either of these scenarios.
**
** Changes are not recorded for individual rows that have NULL values stored
** in one or more of their PRIMARY KEY columns.
**
** SQLITE_OK is returned if the call completes without error. Or, if an error 
** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
**
** <h3>Special sqlite_stat1 Handling</h3>
**
** The "sqlite_stat1" table is an exception to some of the rules above. In
** SQLite, the schema of sqlite_stat1 is:
**  <pre>
**  &nbsp;     CREATE TABLE sqlite_stat1(tbl,idx,stat)  
**  </pre>
**
** Even though sqlite_stat1 does not have a PRIMARY KEY, changes are 
** recorded for it as if the PRIMARY KEY is (tbl,idx). Additionally, changes 
** are recorded for rows for which (idx IS NULL) is true. However, for such
** rows a zero-length blob (SQL value X'') is stored in the changeset or
** patchset instead of a NULL value. This allows such changesets to be
** manipulated by legacy implementations of sqlite3changeset_invert(),
** concat() and similar.
**
** The sqlite3changeset_apply() function automatically converts the 
** zero-length blob back to a NULL value when updating the sqlite_stat1
** table. However, if the application calls sqlite3changeset_new(),
** sqlite3changeset_old() or sqlite3changeset_conflict on a changeset 
** iterator directly (including on a changeset iterator passed to a
** conflict-handler callback) then the X'' value is returned. The application
** must translate X'' to NULL itself if required.
*/
int sqlite3session_attach(
  sqlite3_session *pSession,      /* Session object */
  const char *zTab                /* Table name */
);

/*