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Lib/site-packages/django/db/backends/mysql/compiler.py

@@ -0,0 +1,45 @@
+from django.db.models.sql import compiler
+
+
+class SQLCompiler(compiler.SQLCompiler):
+    def as_subquery_condition(self, alias, columns, compiler):
+        qn = compiler.quote_name_unless_alias
+        qn2 = self.connection.ops.quote_name
+        sql, params = self.as_sql()
+        return '(%s) IN (%s)' % (', '.join('%s.%s' % (qn(alias), qn2(column)) for column in columns), sql), params
+
+
+class SQLInsertCompiler(compiler.SQLInsertCompiler, SQLCompiler):
+    pass
+
+
+class SQLDeleteCompiler(compiler.SQLDeleteCompiler, SQLCompiler):
+    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 = self.query.where.split_having()
+        if self.single_alias or having:
+            # DELETE FROM cannot be used when filtering against aggregates
+            # since it doesn't allow for GROUP BY and HAVING clauses.
+            return super().as_sql()
+        result = [
+            'DELETE %s FROM' % self.quote_name_unless_alias(
+                self.query.get_initial_alias()
+            )
+        ]
+        from_sql, from_params = self.get_from_clause()
+        result.extend(from_sql)
+        where_sql, where_params = self.compile(where)
+        if where_sql:
+            result.append('WHERE %s' % where_sql)
+        return ' '.join(result), tuple(from_params) + tuple(where_params)
+
+
+class SQLUpdateCompiler(compiler.SQLUpdateCompiler, SQLCompiler):
+    pass
+
+
+class SQLAggregateCompiler(compiler.SQLAggregateCompiler, SQLCompiler):
+    pass