ORDER BY后如何使用ROW_NUMBER()函数mysql？

Question

SELECT user.id
      ,user.emp_id
      ,user.name,COUNT(transfer.record_name) AS current_rank
      ,ROW_NUMBER() OVER () AS count
FROM transfer AS transfer
LEFT JOIN users AS user ON user.emp_id= transfer.user_id
WHERE transfer.lobs= 0
AND transfer.shift_date = '2020-03-27'
GROUP BY user.emp_id
ORDER BY current_rank DESC

This query will give me a result of like this:

user.id|   user.emp_id|   user.name|   current_rank|   count
25           1234          test1           4             4
30           4321          test2           2             2
18           5678          test3           1             1
12           8765          test4           1             3

My goal is to use ORDER BY DESC first so that I can order the current_rank and the count column should have the count of:

user.id|   user.emp_id|   user.name|   current_rank|   count
25           1234          test1           4             1
30           4321          test2           2             2
18           5678          test3           1             3
12           8765          test4           1             4

How can I use the ROW_NUMBER() function after I ORDER BY my current_rank column?

Thank you any help. I will appreciate it.

Answer 1

The result of ROW_NUMBER() is not affected by the sort in the query.

Instead, it accepts an ORDER BY option within its OVER clause: without it, the ordering of ROW_NUMBER() is undefined , meaning that the database is free to order the rows as it likes. You may observe that the same ordering is used over consecutive executions, but the database does not guarantee it.

So, do add an ORDER BY to the window function:

ROW_NUMBER() OVER (ORDER BY COUNT(transfer.record_name) DESC) AS count