一个表中的 Mysql 行移动并合并到命名列中答案

【问题标题】：Mysql rows from one table moved and merged into named columns一个表中的 Mysql 行移动并合并到命名列中
【发布时间】：2021-06-29 08:41:13
【问题描述】：

我有以下数据

drop table if exists states;
create table states (id integer, state varchar(100), content varchar(100));
insert into states (id, state, content) values (1, 'soc', '73');
insert into states (id, state, content) values (2, 'range', '412');
insert into states (id, state, content) values (3, 'range', '410');
insert into states (id, state, content) values (3, 'soc', '71');
insert into states (id, state, content) values (5, 'range', '405');

使用以下语句

SELECT id,
       CASE WHEN state = 'range' THEN content ELSE null END AS 'range',
       CASE WHEN state = 'soc' THEN content ELSE null END AS 'soc'
FROM states;

结果是

id	range	soc
1		73
2	412
3	410
3		71
5	405

但我希望将 id 为 3 的两行合并为一行

id	range	soc
1		73
2	412
3	410	71
5	405

必须改变什么才能达到想要的结果？

【问题讨论】：

GROUP BY id 和 MAX(CASE ..)（或 MIN()）。
感谢您的指点，但我能否请您给出更详细的答案，应该如何应用这些陈述？

标签： mysql sql case

【解决方案1】：

SELECT id,
       CASE WHEN state = 'range' THEN content ELSE null END AS 'range',
       CASE WHEN state = 'soc' THEN content ELSE null END AS 'soc'
FROM states;

id	range	soc
1	null	73
2	412	null
3	410	null
3	null	71
5	405	null

SELECT id,
       MAX(CASE WHEN state = 'range' THEN content END) AS 'range',
       MAX(CASE WHEN state = 'soc' THEN content END) AS 'soc'
FROM states
GROUP BY id;

id	range	soc
1	null	73
2	412	null
3	410	71
5	405	null

db小提琴here

【讨论】：