Fixed #28552 -- Dropped support for MySQL 5.5.

3 files changed, 9 insertions, 34 deletions

diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index 0e5c25fc23..1eb3677b80 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -97,14 +97,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
     # types, as strings. Column-type strings can contain format strings; they'll
     # be interpolated against the values of Field.__dict__ before being output.
     # If a column type is set to None, it won't be included in the output.
-    _data_types = {
+    data_types = {
         'AutoField': 'integer AUTO_INCREMENT',
         'BigAutoField': 'bigint AUTO_INCREMENT',
         'BinaryField': 'longblob',
         'BooleanField': 'bool',
         'CharField': 'varchar(%(max_length)s)',
         'DateField': 'date',
-        'DateTimeField': 'datetime',
+        'DateTimeField': 'datetime(6)',
         'DecimalField': 'numeric(%(max_digits)s, %(decimal_places)s)',
         'DurationField': 'bigint',
         'FileField': 'varchar(%(max_length)s)',
@@ -121,17 +121,10 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         'SlugField': 'varchar(%(max_length)s)',
         'SmallIntegerField': 'smallint',
         'TextField': 'longtext',
-        'TimeField': 'time',
+        'TimeField': 'time(6)',
         'UUIDField': 'char(32)',
     }
 
-    @cached_property
-    def data_types(self):
-        if self.features.supports_microsecond_precision:
-            return dict(self._data_types, DateTimeField='datetime(6)', TimeField='time(6)')
-        else:
-            return self._data_types
-
     # For these columns, MySQL doesn't:
     # - accept default values and implicitly treats these columns as nullable
     # - support a database index
diff --git a/django/db/backends/mysql/features.py b/django/db/backends/mysql/features.py
index 18ab088941..542b621aa9 100644
--- a/django/db/backends/mysql/features.py
+++ b/django/db/backends/mysql/features.py
@@ -61,10 +61,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         return self._mysql_storage_engine != 'MyISAM'
 
     @cached_property
-    def supports_microsecond_precision(self):
-        return self.connection.mysql_version >= (5, 6, 4)
-
-    @cached_property
     def has_zoneinfo_database(self):
         # Test if the time zone definitions are installed.
         with self.connection.cursor() as cursor:
diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index e4492f866f..474cd8d467 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -109,10 +109,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         return "INTERVAL '%06f' SECOND_MICROSECOND" % timedelta.total_seconds()
 
     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
+        return 'INTERVAL %s MICROSECOND' % sql
 
     def force_no_ordering(self):
         """
@@ -178,10 +175,6 @@ class DatabaseOperations(BaseDatabaseOperations):
                 value = timezone.make_naive(value, self.connection.timezone)
             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 str(value)
 
     def adapt_timefield_value(self, value):
@@ -258,17 +251,10 @@ class DatabaseOperations(BaseDatabaseOperations):
     def subtract_temporals(self, internal_type, lhs, rhs):
         lhs_sql, lhs_params = lhs
         rhs_sql, rhs_params = rhs
-        if self.connection.features.supports_microsecond_precision:
-            if internal_type == 'TimeField':
-                return (
-                    "((TIME_TO_SEC(%(lhs)s) * POW(10, 6) + MICROSECOND(%(lhs)s)) -"
-                    " (TIME_TO_SEC(%(rhs)s) * POW(10, 6) + MICROSECOND(%(rhs)s)))"
-                ) % {'lhs': lhs_sql, 'rhs': rhs_sql}, lhs_params * 2 + rhs_params * 2
-            else:
-                return "TIMESTAMPDIFF(MICROSECOND, %s, %s)" % (rhs_sql, lhs_sql), rhs_params + lhs_params
-        elif internal_type == 'TimeField':
+        if internal_type == 'TimeField':
             return (
-                "(TIME_TO_SEC(%s) * POW(10, 6) - TIME_TO_SEC(%s) * POW(10, 6))"
-            ) % (lhs_sql, rhs_sql), lhs_params + rhs_params
+                "((TIME_TO_SEC(%(lhs)s) * POW(10, 6) + MICROSECOND(%(lhs)s)) -"
+                " (TIME_TO_SEC(%(rhs)s) * POW(10, 6) + MICROSECOND(%(rhs)s)))"
+            ) % {'lhs': lhs_sql, 'rhs': rhs_sql}, lhs_params * 2 + rhs_params * 2
         else:
-            return "(TIMESTAMPDIFF(SECOND, %s, %s) * POW(10, 6))" % (rhs_sql, lhs_sql), rhs_params + lhs_params
+            return "TIMESTAMPDIFF(MICROSECOND, %s, %s)" % (rhs_sql, lhs_sql), rhs_params + lhs_params