MySQL：使用增量列更新重复记录

Question

- 创造

CREATE TABLE employee 
(
  emp_id INTEGER,
  job_code TEXT,
  cnt_check int
);

- 插入

INSERT INTO employee(emp_id,job_code) VALUES (0001, 'JC001');
INSERT INTO employee(emp_id,job_code) VALUES (0001, 'JC001');
INSERT INTO employee(emp_id,job_code) VALUES (0002, 'JC002');
INSERT INTO employee(emp_id,job_code) VALUES (0002, 'JC002');
INSERT INTO employee(emp_id,job_code) VALUES (0003, 'JC003');
INSERT INTO employee(emp_id,job_code) VALUES (0004, 'JC004');
INSERT INTO employee(emp_id,job_code) VALUES (0004, 'JC004');
INSERT INTO employee(emp_id,job_code) VALUES (0004, 'JC004');

预期产出:

emp_id  job_code  cnt_check
--------------------------------
0001    JC001       1
0001    JC001       2
0002    JC002       1
0002    JC002       2
0003    JC003       1
0004    JC004       1
0004    JC004       2
0004    JC004       3

我的尝试：

update tbl_student t1
join 
(
select usn,applicationid,row_number() over(partition by usn,applicationid) rnk
from tbl_student
) t2 
on t1.usn = t2.usn and t1.applicationid = t2.applicationid
set t1.no_pay = t2.rnk;

但是所有记录都更新为值 1。

Demo Link

Answer 1

使用示例数据中的确切列，我们可以尝试：

SELECT emp_id, job_code,
       ROW_NUMBER() OVER (PARTITION BY emp_id ORDER BY emp_id) AS cnt_check
FROM employee
ORDER BY 1, 3;