Fixed #24584 -- Fixed microsecond handling with older MySQLdb

django/db/backends/mysql/operations.py

@@ -77,7 +77,10 @@ class DatabaseOperations(BaseDatabaseOperations):
             timedelta.days, timedelta.seconds, timedelta.microseconds), []
 
     def format_for_duration_arithmetic(self, sql):
+        if self.connection.features.supports_microsecond_precision:
             return 'INTERVAL %s MICROSECOND' % sql
+        else:
+            return 'INTERVAL FLOOR(%s / 1000000) SECOND' % sql
 
     def drop_foreignkey_sql(self):
         return "DROP FOREIGN KEY"
@@ -146,6 +149,9 @@ class DatabaseOperations(BaseDatabaseOperations):
             else:
                 raise ValueError("MySQL backend does not support timezone-aware datetimes when USE_TZ is False.")
 
+        if not self.connection.features.supports_microsecond_precision:
+            value = value.replace(microsecond=0)
+
         return six.text_type(value)
 
     def value_to_db_time(self, value):

docs/releases/1.8.1.txt

@@ -21,3 +21,7 @@ Bugfixes
 * Fixed :djadmin:`squashmigrations` command when using
   :class:`~django.db.migrations.operations.SeparateDatabaseAndState`
   (:ticket:`24278`).
+
+* Stripped microseconds from ``datetime`` values when using an older version of
+  the MySQLdb DB API driver as it does not support fractional seconds
+  (:ticket:`24584`).

tests/basic/tests.py

@@ -192,15 +192,30 @@ class ModelTest(TestCase):
 
     @skipIfDBFeature('supports_microsecond_precision')
     def test_microsecond_precision_not_supported(self):
-        # In MySQL, microsecond-level precision isn't available. You'll lose
-        # microsecond-level precision once the data is saved.
+        # In MySQL, microsecond-level precision isn't always available. You'll
+        # lose microsecond-level precision once the data is saved.
         a9 = Article(
             headline='Article 9',
             pub_date=datetime(2005, 7, 31, 12, 30, 45, 180),
         )
         a9.save()
-        self.assertEqual(Article.objects.get(id__exact=a9.id).pub_date,
-            datetime(2005, 7, 31, 12, 30, 45))
+        self.assertEqual(
+            Article.objects.get(id__exact=a9.id).pub_date,
+            datetime(2005, 7, 31, 12, 30, 45),
+        )
+
+    @skipIfDBFeature('supports_microsecond_precision')
+    def test_microsecond_precision_not_supported_edge_case(self):
+        # In MySQL, microsecond-level precision isn't always available. You'll
+        # lose microsecond-level precision once the data is saved.
+        a = Article.objects.create(
+            headline='Article',
+            pub_date=datetime(2008, 12, 31, 23, 59, 59, 999999),
+        )
+        self.assertEqual(
+            Article.objects.get(pk=a.pk).pub_date,
+            datetime(2008, 12, 31, 23, 59, 59),
+        )
 
     def test_manually_specify_primary_key(self):
         # You can manually specify the primary key when creating a new object.