diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 5fe12a9f09..54f1e56d77 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -332,11 +332,11 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         'istartswith': "LIKE UPPER(TRANSLATE(%s USING NCHAR_CS)) ESCAPE TRANSLATE('\\' USING NCHAR_CS)",
         'iendswith': "LIKE UPPER(TRANSLATE(%s USING NCHAR_CS)) ESCAPE TRANSLATE('\\' USING NCHAR_CS)",
     }
-    oracle_version = None
 
     def __init__(self, *args, **kwargs):
         super(DatabaseWrapper, self).__init__(*args, **kwargs)
 
+        self.oracle_version = None
         self.features = DatabaseFeatures(self)
         self.ops = DatabaseOperations()
         self.client = DatabaseClient(self)
@@ -349,9 +349,9 @@ class DatabaseWrapper(BaseDatabaseWrapper):
 
     def _connect_string(self):
         settings_dict = self.settings_dict
-        if len(settings_dict['HOST'].strip()) == 0:
+        if settings_dict['HOST'].strip():
             settings_dict['HOST'] = 'localhost'
-        if len(settings_dict['PORT'].strip()) != 0:
+        if settings_dict['PORT'].strip():
             dsn = Database.makedsn(settings_dict['HOST'],
                                    int(settings_dict['PORT']),
                                    settings_dict['NAME'])