如何计算 MySQL 中 pivot 表的值？

Question

I have two tables Users and Get_cal like below:

Users

id_user(pk)	com
1004	700
1005	700
1006	700
1010	701
1011	701
1012	701
1013	701
1014	800
1015	800
1016	800
1017	800

Get_cal

id_user(fk)	status
1004	ABAN
1004	ABAN
1004	DES
1004	LET
1004	DES
1004	ABAN
1011	LET
1011	LET
1011	ABAN
1015	ABAN
1015	DES
1015	LET
1015	LET

For status column I have 5 types (ABAN,DES,LET,NOANS,OTH) . I want to get this result like below( Get the count by user by status ):

id_user	ABAN	DES	LET	NOANS	OTH
1004	3	2	1	0	0
1005	0	0	0	0	0
1006	0	0	0	0	0
1010	0	0	0	0	0
1011	1	0	2	0	0
1012	0	0	0	0	0
1013	0	0	0	0	0
1014	0	0	0	0	0
1015	1	1	2	0	0
1016	0	0	0	0	0
1017	0	0	0	0	0

I have no idea how to start the query, please any suggestion?

Answer 1

You want conditional aggregation here:

SELECT
    u.id_user,
    COUNT(CASE WHEN c.status = 'ABAN'  THEN 1 END) AS ABAN,
    COUNT(CASE WHEN c.status = 'DES'   THEN 1 END) AS DES,
    COUNT(CASE WHEN c.status = 'LET'   THEN 1 END) AS LET,
    COUNT(CASE WHEN c.status = 'NOANS' THEN 1 END) AS NOANS,
    COUNT(CASE WHEN c.status NOT IN ('ABAN', 'DES', 'LET', 'NOAN')
               THEN 1 END) AS OTH
FROM Users u
LEFT JOIN Get_cal c
    ON c.id_user = u.id_user
GROUP BY
    u.id_user
ORDER BY
    u.id_user;

Answer 2

If your status is always static with that 5 cases. you can use left join and group by and some switch case conditions to solve the query.

SELECT Users.id_user ,
SUM(CASE WHEN Get_cal.status = 'ABAN' THEN 1 ELSE 0 END) AS ABAN ,
SUM(CASE WHEN Get_cal.status = 'DES' THEN 1 ELSE 0 END) AS DES ,
SUM(CASE WHEN Get_cal.status = 'LET' THEN 1 ELSE 0 END) AS LET ,
SUM(CASE WHEN Get_cal.status = 'NOANS' THEN 1 ELSE 0 END) AS NOANS ,
SUM(CASE WHEN Get_cal.status = 'OTH' THEN 1 ELSE 0 END) AS OTH 
FROM Users LEFT JOIN Get_cal ON (Users.id_user = Get_cal.id_user) GROUP BY Users.id_user ,Get_cal.id_user