MySQL & Python select 最后对应的行而不是第一行

Question

I had a quick question. I want to count how many times a user is logged into the system. To achieve this i add a 1 to the third part of the result. The only thing is that every time the user logs in the code fetches the first corresponding row. Thus resulting in the fact that the login_num will always be 2, since the first corresponding row always contains a 1.

On Stackoverflow i searched for several solutions. So i came up with the DESC at the end of the fetch syntax. However in every instance i tried this, i always end up getting an error in return. Does anyone have an idea why this is the case?

Python code:

cursor.execute("Select rfid_uid, name, login_num FROM users rfid_uid="+str(id) + "ORDER BY id DESC")
result = cursor.fetchone()

if cursor.rowcount >= 1:
  print("Welkom " + result[1])
  print(result)
  result = (result[0], result[1], result[2] + 1)
  sql_insert = "INSERT INTO users (rfid_uid, name, login_num) VALUES (%s, %s, %s)"
  cursor.execute(sql_insert, (result))
  db.commit()

Answer 1

Seems your SQL statement refers to table 'users'. I suppose it does contain info about users in general (a row per user), not user logins.

If you have each individual user login event registered in some table, I would let the database do the counting. Something like this:

SELECT COUNT(*) FROM user_logins WHERE rfid_uid='user_id';

You should get one row, which has your answer as an integer.