如下表Z 中，取 字段a 最大的那行

字段a 字段a 字段cSP000016964 5 20SP000016964 7 30SP000016964 1 15SP000017755 4 16SP000017755 8 12

最后得到下面結(jié)果

SP000016964 7 30SP000017755 8 12

代碼如下 復(fù)制代碼 SQL語句如下：select z.* from z, (select a,max(b) as max_b from z group by a) z1 where z.a = z1.a and z.b = z1.max_b

下面給大家詳細(xì)總結(jié)一些方法

SQL Server 按某一字段分組 取 最大 (小)值所在行的數(shù)據(jù) -- 按某一字段分組 取 最大 (小)值所在行的數(shù)據(jù) -- (愛新覺羅.毓華(十八年風(fēng)雨,守得冰山雪蓮花開) 2007-10-23于浙江杭州)

代碼如下 復(fù)制代碼 /* 數(shù)據(jù)如下：name val memoa 2 a2(a的第二個(gè)值)a 1 a1--a的第一個(gè)值a 3 a3:a的第三個(gè)值b 1 b1--b的第一個(gè)值b 3 b3:b的第三個(gè)值b 2 b2b2b2b2b 4 b4b4b 5 b5b5b5b5b5*/ -- 創(chuàng)建表并插入數(shù)據(jù)： create table tb(name varchar ( 10 ),val int ,memo varchar ( 20 ))insert into tb values ( ' a ' , 2 , ' a2(a的第二個(gè)值) ' )insert into tb values ( ' a ' , 1 , ' a1--a的第一個(gè)值 ' )insert into tb values ( ' a ' , 3 , ' a3:a的第三個(gè)值 ' )insert into tb values ( ' b ' , 1 , ' b1--b的第一個(gè)值www.111Cn.net ' )insert into tb values ( ' b ' , 3 , ' b3:b的第三個(gè)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(shù)據(jù)。 -- 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(gè)值b 5 b5b5b5b5b5*/

-- 二、按name分組 取 val最小的值所在行的數(shù)據(jù)。 -- 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(gè)值b 1 b1--b的第一個(gè)值*/

-- 三、按name分組 取 第一次出現(xiàn)的行所在的數(shù)據(jù)。 select a. * from tb a where val = ( select top 1 val from tb where name = a.name) order by a.name/* name val memo ---------- ----------- -------------------- a 2 a2(a的第二個(gè)值)b 1 b1--b的第一個(gè)值*/

-- 四、按name分組 隨機(jī)取 一條數(shù)據(jù)www.111cn.net。 select a. * from tb a where val = ( select top 1 val from tb where name = a.name order by newid ()) order by a.name/* name val memo ---------- ----------- -------------------- a 1 a1--a的第一個(gè)值b 5 b5b5b5b5b5*/

-- 五、按name分組 取 最小的兩個(gè)(N個(gè))val select a. * from tb a where 2 > ( select count ( * ) from tb where name = a.name and val < a.val ) order by a.name,a.valselect a. * from tb a where val in ( select top 2 val from tb where name = a.name order by val) order by a.name,a.valselect a. * from tb a where exists ( select count ( * ) from tb where name = a.name and val < a.val having Count ( * ) < 2 ) order by a.name/* name val memo ---------- ----------- -------------------- a 1 a1--a的第一個(gè)值a 2 a2(a的第二個(gè)值)b 1 b1--b的第一個(gè)值b 2 b2b2b2b2*/

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