Thank you, Chris.
Now, I need to do this in PHP:
-------------------- CODE ---------------------------------------------------------------
$errorCode = pg_result_error_field($res1, PGSQL_DIAG_SQLSTATE) ;
if( $errorCode == UNIQUE_VIOLATION )
echo( "message 1" );
else if( $errorCode == DATETIME_FIELD_OVERFLOW )
echo( "message 2" );
-------------------- CODE ---------------------------------------------------------------
Thank you, again.