compiler.py 文件源码

def get_combinator_sql(self, combinator, all):
        features = self.connection.features
        compilers = [
            query.get_compiler(self.using, self.connection)
            for query in self.query.combined_queries
        ]
        if not features.supports_slicing_ordering_in_compound:
            for query, compiler in zip(self.query.combined_queries, compilers):
                if query.low_mark or query.high_mark:
                    raise DatabaseError('LIMIT/OFFSET not allowed in subqueries of compound statements.')
                if compiler.get_order_by():
                    raise DatabaseError('ORDER BY not allowed in subqueries of compound statements.')
        parts = (compiler.as_sql() for compiler in compilers)
        combinator_sql = self.connection.ops.set_operators[combinator]
        if all and combinator == 'union':
            combinator_sql += ' ALL'
        braces = '({})' if features.supports_slicing_ordering_in_compound else '{}'
        sql_parts, args_parts = zip(*((braces.format(sql), args) for sql, args in parts))
        result = [' {} '.format(combinator_sql).join(sql_parts)]
        params = []
        for part in args_parts:
            params.extend(part)
        return result, params