Fix the missing fields in database classes

data_diff/databases/mssql.py

@@ -173,6 +173,7 @@ class MsSQL(ThreadedDatabase):
 
     default_database: str
     _args: Dict[str, Any]
+    _mssql: Any
 
     def __init__(self, host, port, user, password, *, database, thread_count, **kw):
         args = dict(server=host, port=port, database=database, user=user, password=password, **kw)
@@ -188,6 +189,7 @@ def __init__(self, host, port, user, password, *, database, thread_count, **kw):
         except KeyError:
             raise ValueError("Specify a default database and schema.")
 
+        self._mssql = None
         super().__init__(thread_count=thread_count)
 
     def create_connection(self):

data_diff/databases/oracle.py

@@ -189,11 +189,13 @@ class Oracle(ThreadedDatabase):
     CONNECT_URI_PARAMS = ["database?"]
 
     kwargs: Dict[str, Any]
+    _oracle: Any
 
     def __init__(self, *, host, database, thread_count, **kw):
         super().__init__(thread_count=thread_count)
         self.kwargs = dict(dsn=f"{host}/{database}" if database else host, **kw)
         self.default_schema = kw.get("user").upper()
+        self._oracle = None
 
     def create_connection(self):
         self._oracle = import_oracle()