MYSQL 为每组设置基于列的第一条记录

Question

I have a table which can be recreated as

create table test
 (employeeID int,
  date Date,
  TookTest int
 );

insert into test(employeeID, date, TookTest)
values
(1, '2014-01-01', 1),
(1, '2014-01-02', 1),
(1, '2014-01-03', 1),
(2, '2014-01-01', 1),
(2, '2014-01-20', 1),
(3, '2014-01-01', 1),
(3, '2014-01-21', 1),
(4, '2014-01-03', 1),
(4, '2014-01-27', 1)

I am trying to set the first record of every group to be 0 in the newCol

employeeID  date        TookTest  newCol
----------------------------------------
1         2014-01-01      1         0
1         2014-01-02      1         1
1         2014-01-03      1         1
2         2014-01-01      1         0
2         2014-01-20      1         1
3         2014-01-01      1         0
3         2014-01-21      1         1
4         2014-01-03      1.        0
4         2014-01-27      1.        1

How do I go about this?

Answer 1

UPDATE test t1
JOIN ( SELECT t2.employeeID, MIN(t2.`date`) `date`
       FROM test t2
       GROUP BY 1 ) t3 USING (employeeID, `date`)
SET t1.TookTest = 0;