Mysql按表字段分组排序，取每组数据的最值

一、需求说明

例如：有一张记录用户成绩的表 t_goal，表字段以及表数据如下：

id	uuid	goal	time
1	56a2e88e-54f4-49f6-83dd-592ce1da63bc	90	2022-05-18 09:00:00
2	56a2e88e-54f4-49f6-83dd-592ce1da63bc	92	2022-05-19 09:00:00
3	56a2e88e-54f4-49f6-83dd-592ce1da63bc	88	2022-05-20 09:00:00
4	80be960f-cb32-4cf1-81f0-fcd5a11c92ba	92	2022-05-18 09:00:00
5	80be960f-cb32-4cf1-81f0-fcd5a11c92ba	94	2022-05-19 09:00:00
6	80be960f-cb32-4cf1-81f0-fcd5a11c92ba	96	2022-05-20 09:00:00
7	e099ba5e-27c5-4419-8bd9-7dbcb1e00cad	86	2022-05-18 09:00:00
8	e099ba5e-27c5-4419-8bd9-7dbcb1e00cad	80	2022-05-19 09:00:00
9	e099ba5e-27c5-4419-8bd9-7dbcb1e00cad	97	2022-05-20 09:00:00

需要查出每个人历史最高成绩

二、sql文

SELECT * FROM (
SELECT
DISTINCT
	uuid,
	goal,
	`time`,
	rank() over( PARTITION BY uuid ORDER BY goal DESC, `time` DESC ) rownum
FROM
	t_goal)tmp
	WHERE tmp.rownum = 1

外层未指定排序，则结果集默认按uuid，goal，time进行排序

uuid	goal	time
56a2e88e-54f4-49f6-83dd-592ce1da63bc	92	2022-05-19 09:00:00
80be960f-cb32-4cf1-81f0-fcd5a11c92ba	96	2022-05-20 09:00:00
e099ba5e-27c5-4419-8bd9-7dbcb1e00cad	97	2022-05-20 09:00:00

三、rank() over()函数说明

rank() over( ORDER BY goal DESC, `time` DESC )
rank() over( PARTITION BY uuid ORDER BY goal DESC, `time` DESC )

PARTITION BY：用于给结果集分组，可有多个字段。可为空。
（如果没有指定字段PARTITION BY，则把整个结果集作为一个分组）

ORDER BY：用于给结果集排序，可有多个字段