Method as_sql

django/db/backends/mysql/compiler.py:18–41

(self)

class SQLDeleteCompiler(BaseSQLDeleteCompiler):
    def as_sql(self):
        # Prefer the non-standard DELETE FROM syntax over the SQL generated by
        # the SQLDeleteCompiler's default implementation when multiple tables
        # are involved since MySQL/MariaDB will generate a more efficient query
        # plan than when using a subquery.
        where, having, qualify = self.query.where.split_having_qualify(
            must_group_by=self.query.group_by is not None
        )
        if self.single_alias or having or qualify:
            # DELETE FROM cannot be used when filtering against aggregates or
            # window functions as it doesn't allow for GROUP BY/HAVING clauses
            # and the subquery wrapping (necessary to emulate QUALIFY).
            return super().as_sql()
        result = ["DELETE %s FROM" % self.quote_name(self.query.get_initial_alias())]
        from_sql, params = self.get_from_clause()
        result.extend(from_sql)
        try:
            where_sql, where_params = self.compile(where)
        except FullResultSet:
            pass
        else:
            result.append("WHERE %s" % where_sql)
            params.extend(where_params)
        return " ".join(result), tuple(params)


class SQLUpdateCompiler(BaseSQLUpdateCompiler):