mysql - 根据行数将数据从行连接到 1 行

Question

我有下表:

user
userId   name
1        Sam
2        Harold
3        John


othertable
id      id2      number
1       111      12
1       222      23
1       333      33
2       111      12
2       444      11
3       555      12
3       222      44

用户表的 userId 与其他表的 id 列匹配。理想情况下，我想根据该 id 存在的行数将 othertable 的内容加入到用户中。这就是我想要的输出:

e.g.
user
    userId   name    111    222   333   444   555
    1        Sam     12     12    33
    2        Harold  12                 11
    3        John           44                12

有什么想法吗？

更新:id2 的值是有限的。仅有效值 111、222、333、444 和 555。

Answer 1

您可以尝试一下这个1...不确定它是否满足您的要求...

CREATE TABLE users 
(
    userId int,
    name varchar(max)
) 

INSERT INTO USERS VALUES
(1, 'Sam'),
(2, 'Harold'),
(3, 'John')

CREATE TABLE othertable 
(
    id int,
    id2 int,
    number int
)

INSERT INTO othertable VALUES
(1, 111, 12),
(1, 222, 23),
(1, 333, 33),
(2, 111, 12),
(2, 444, 11),
(3, 555, 12),
(3, 222, 44)

SELECT
    u.userId,
    u.name,
    SUM(CASE WHEN (id2=111) THEN number ELSE 0 END) AS [111],
    SUM(CASE WHEN (id2=222) THEN number ELSE 0 END) AS [222],
    SUM(CASE WHEN (id2=333) THEN number ELSE 0 END) AS [333],
    SUM(CASE WHEN (id2=444) THEN number ELSE 0 END) AS [444],
    SUM(CASE WHEN (id2=555) THEN number ELSE 0 END) AS [555]
FROM othertable o 
INNER JOIN users u ON o.id = u.userId
GROUP BY u.userId, u.name

请尝试一下。 :)

UPDATE: Sorry, I'm not really familiar with MySQL. But I did tried my best by changing the query into subquery and hope this can help you. If this doesn't meet you requirement, I hope some other people can help you.

UPDATE 2: Avoid using PIVOT