Fixed #24675 -- Skipped SQL_AUTO_IS_NULL query on MySQL if not needed.

django/db/backends/mysql/base.py

@@ -267,12 +267,13 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         return conn
 
     def init_connection_state(self):
-        with self.cursor() as cursor:
-            # SQL_AUTO_IS_NULL in MySQL controls whether an AUTO_INCREMENT column
-            # on a recently-inserted row will return when the field is tested for
-            # NULL.  Disabling this value brings this aspect of MySQL in line with
-            # SQL standards.
-            cursor.execute('SET SQL_AUTO_IS_NULL = 0')
+        if self.features.is_sql_auto_is_null_enabled:
+            with self.cursor() as cursor:
+                # SQL_AUTO_IS_NULL controls whether an AUTO_INCREMENT column on
+                # a recently inserted row will return when the field is tested
+                # for NULL. Disabling this brings this aspect of MySQL in line
+                # with SQL standards.
+                cursor.execute('SET SQL_AUTO_IS_NULL = 0')
 
     def create_cursor(self):
         cursor = self.connection.cursor()

django/db/backends/mysql/features.py

@@ -69,3 +69,9 @@ class DatabaseFeatures(BaseDatabaseFeatures):
 
     def introspected_boolean_field_type(self, *args, **kwargs):
         return 'IntegerField'
+
+    @cached_property
+    def is_sql_auto_is_null_enabled(self):
+        with self.connection.cursor() as cursor:
+            cursor.execute('SELECT @@SQL_AUTO_IS_NULL')
+            return cursor.fetchone()[0] == 1

tests/backends/test_mysql.py

@@ -0,0 +1,20 @@
+from __future__ import unicode_literals
+
+import unittest
+
+from django.db import connection
+from django.test import TestCase, override_settings
+
+
+@override_settings(DEBUG=True)
+@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL specific test.')
+class MySQLTests(TestCase):
+
+    def test_auto_is_null_auto_config(self):
+        query = 'set sql_auto_is_null = 0'
+        connection.init_connection_state()
+        last_query = connection.queries[-1]['sql'].lower()
+        if connection.features.is_sql_auto_is_null_enabled:
+            self.assertIn(query, last_query)
+        else:
+            self.assertNotIn(query, last_query)