SQL Server gets one of the most valued data in each category

/* 数据如下： name val memo a    2   a2(a的第二个值) a    1   a1--a的第一个值 a    3   a3:a的第三个值 b    1   b1--b的第一个值 b    3   b3:b的第三个值 b    2   b2b2b2b2 b    4   b4b4 b    5   b5b5b5b5b5 */--创建表并插入数据： create table tb(name varchar(10),val int,memo varchar(20)) insert into tb values(‘a‘,    2,   ‘a2(a的第二个值)‘) insert into tb values(‘a‘,    1,   ‘a1--a的第一个值‘) insert into tb values(‘a‘,    3,   ‘a3:a的第三个值‘) insert into tb values(‘b‘,    1,   ‘b1--b的第一个值‘) insert into tb values(‘b‘,    3,   ‘b3:b的第三个值‘) insert into tb values(‘b‘,    2,   ‘b2b2b2b2‘) insert into tb values(‘b‘,    4,   ‘b4b4‘) insert into tb values(‘b‘,    5,   ‘b5b5b5b5b5‘) go   --一、按name分组取val最大的值所在行的数据。 --方法1： select a.* from tb a where val = (select max(val) from tb where name = a.name) order by a.name--方法2： select a.* from tb a where not exists(select 1 from tb where name = a.name and val > a.val) --方法3： select a.* from tb a,(select name,max(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name--方法4： select a.* from tb a inner join (select name , max(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name--方法5 select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name/* name       val         memo                  ---------- ----------- --------------------  a          3           a3:a的第三个值 b          5           b5b5b5b5b5 */

Notation 6

SELECT * FROM (SELECT *, Row_number () + (PARTITION by name ORDER by Val DESC) RID from TB) as T WHERE RID = 1

If there is more than two of the same Val in a name group above, query method 1-5 is incorrect.

For example:

INSERT into TB values (' A ', 2, ' A2 (second value of a) ')
INSERT into TB values (' A ', 3, ' A1--a's first value ')
INSERT into TB values (' A ', 3, ' A3:a's third value ')

SQL Server gets one of the most valued data in each category