Returns the last value inserted into an IDENTITY column or a DEFAULT AUTOINCREMENT column, or zero if the most recent insert
was into a table that did not contain an IDENTITY or DEFAULT AUTOINCREMENT column.
The sasql_insert_id function is provided for compatibility with MySQL databases.
The ID generated for an AUTOINCREMENT column by a previous INSERT statement or zero if last insert did not affect an AUTOINCREMENT
column. The function can return FALSE if the $conn is not valid.