protected function _convertOnClause($clause)
    {
        if ($clause === 'CASCADE' || $clause === 'RESTRICT') {
            return strtolower($clause);
        }
        if ($clause === 'NO ACTION') {
            return TableSchema::ACTION_NO_ACTION;
        }

        return TableSchema::ACTION_SET_NULL;
    }
protected function _convertOnClause($clause)
    {
        if ($clause === 'CASCADE' || $clause === 'RESTRICT') {
            return strtolower($clause);
        }
        if ($clause === 'NO ACTION') {
            return TableSchema::ACTION_NO_ACTION;
        }

        return TableSchema::ACTION_SET_NULL;
    }
protected function _convertOnClause ( $ clause ) { if ( $ clause === 'CASCADE' || $ clause === 'RESTRICT' ) { return strtolower ( $ clause ) ; } if ( $ clause === 'NO ACTION' ) { return TableSchema :: ACTION_NO_ACTION ; } return TableSchema :: ACTION_SET_NULL ; }
Convert string on clauses to the abstract ones.

@param string $clause The on clause to convert.
@return string|null
Convert string on clauses to the abstract ones .