/* 數據如下： name val memo a 2 a2(a的第二個值) a 1 a1--a的第一個值 a 3 a3:a的第三個值 b 1 b1--b的第一個值 b 3 b3:b的第三個值 b 2 b2b2b2b2 b 4 b4b4 b 5 b5b5b5b5b5 */
--創建表并插入數據：
復制代碼 代碼如下:
create table tb(name varchar(10),val int,memo varchar(20)) insert into tb values('a', 2, 'a2(a的第二個值)') insert into tb values('a', 1, 'a1--a的第一個值') insert into tb values('a', 3, 'a3:a的第三個值') insert into tb values('b', 1, 'b1--b的第一個值') insert into tb values('b', 3, 'b3:b的第三個值') 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分組取val最大的值所在行的數據。
復制代碼 代碼如下:
--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的第三個值 b 5 b5b5b5b5b5
--方法1：select a.* from tb a where val = (select min(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,min(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 , min(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 1 a1--a的第一個值 b 1 b1--b的第一個值
