fix auto sign out

model.py

@@ -205,12 +205,12 @@ def drop_old_sessions():
     connect()
 
     cursor.execute('''
-                DELETE FROM sessions s1
+                DELETE FROM sessions
                 WHERE 
                     (SELECT COUNT(*) as newer
                      FROM sessions s2
-                     WHERE s1.user_id = s2.user_id
-                     AND s1.rowid < s2.rowid) >= 10
+                     WHERE user_id = s2.user_id
+                     AND rowid < s2.rowid) >= 10
                 ''')
 
 
@@ -872,6 +872,6 @@ def sign_out_user(session_id):
     connect()
 
     cursor.execute('''
-        DELETE FROM sessions s1
-        WHERE user_id = (SELECT user_id FROM sessions s2 WHERE session_id = ?)
+        DELETE FROM sessions
+        WHERE user_id = (SELECT user_id FROM sessions s2 WHERE s2.session_id = ?)
         ''', (session_id,))