protected function _process( array $stmts )
	{
		$this->_msg( 'Adding constraint for table mshop_product_tag', 0 ); $this->_status( '' );

		if( $this->_schema->tableExists( 'mshop_product_tag' ) === true )
		{
			foreach ( $stmts as $constraint=>$stmt )
			{
				$this->_msg( sprintf( 'Checking constraint "%1$s": ', $constraint ), 1 );

				if( $this->_schema->constraintExists( 'mshop_product_tag', $constraint ) === false )
				{
					$this->_execute( $stmt );
					$this->_status( 'added' );
				}
				else
				{
					$this->_status( 'OK' );
				}
			}
		}
	}