[2.0.x] Fixed #28804 -- Fixed "Unknown system variable 'transaction_isolation'" on MariaDB.

Regression in 967450a3bf940c43db891fe1e2ef3bcf73456ff8.

Backport of e3c852cbd609484b272f563f3c21066fb12ef7f8 from master

1 files changed, 3 insertions, 10 deletions

diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index 7690629209..7ab3bc8d0d 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -228,9 +228,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
                         isolation_level,
                         ', '.join("'%s'" % s for s in sorted(self.isolation_levels))
                     ))
-            # The variable assignment form of setting transaction isolation
-            # levels will be used, e.g. "set transaction_isolation='repeatable-read'".
-            isolation_level = isolation_level.replace(' ', '-')
         self.isolation_level = isolation_level
         kwargs.update(options)
         return kwargs
@@ -238,10 +235,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
     def get_new_connection(self, conn_params):
         return Database.connect(**conn_params)
 
-    @cached_property
-    def transaction_isolation_variable(self):
-        return 'tx_isolation' if self.mysql_version < (5, 7, 20) else 'transaction_isolation'
-
     def init_connection_state(self):
         assignments = []
         if self.features.is_sql_auto_is_null_enabled:
@@ -249,14 +242,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             # 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.
-            assignments.append('SQL_AUTO_IS_NULL = 0')
+            assignments.append('SET SQL_AUTO_IS_NULL = 0')
 
         if self.isolation_level:
-            assignments.append("%s = '%s'" % (self.transaction_isolation_variable, self.isolation_level))
+            assignments.append('SET SESSION TRANSACTION ISOLATION LEVEL %s' % self.isolation_level.upper())
 
         if assignments:
             with self.cursor() as cursor:
-                cursor.execute('SET ' + ', '.join(assignments))
+                cursor.execute('; '.join(assignments))
 
     def create_cursor(self, name=None):
         cursor = self.connection.cursor()