请问SQL查询语句中如何让多列重复的记录只保留一条记录，其它的数据正常显示

select t.* from tb t where t1 = (select min(t1) from tb where t3 = t.t3 and t4 = t.t4 and t5 = t.t5)

select t.* from tb t where t1 = (select max(t1) from tb where t3 = t.t3 and t4 = t.t4 and t5 = t.t5)

--按某一字段分组取最大(小)值所在行的数据

(爱新觉罗.毓华 2007-10-23于浙江杭州)

/*

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

*/



--二、按name分组取val最小的值所在行的数据。

--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的第一个值

b          1           b1--b的第一个值

*/



--三、按name分组取第一次出现的行所在的数据。

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的第二个值)

b          1           b1--b的第一个值

*/



--四、按name分组随机取一条数据。

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的第一个值

b          5           b5b5b5b5b5

*/



--五、按name分组取最小的两个(N个)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.val

select 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.val

select 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的第一个值

a          2           a2(a的第二个值)

b          1           b1--b的第一个值

b          2           b2b2b2b2

*/



--六、按name分组取最大的两个(N个)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.val

select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val desc) order by a.name,a.val

select 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          2           a2(a的第二个值)

a          3           a3:a的第三个值

b          4           b4b4

b          5           b5b5b5b5b5

*/

--七，如果整行数据有重复，所有的列都相同。

/*

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    1   a1--a的第一个值

a    3   a3:a的第三个值

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

*/

--在sql server 2000中只能用一个临时表来解决，生成一个自增列，先对val取最大或最小，然后再通过自增列来取数据。

--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',    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('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



select * , px = identity(int,1,1) into tmp from tb



select m.name,m.val,m.memo from

(

  select t.* from tmp t where val = (select min(val) from tmp where name = t.name)

) m where px = (select min(px) from

(

  select t.* from tmp t where val = (select min(val) from tmp where name = t.name)

) n where n.name = m.name)



drop table tb,tmp



/*

name       val         memo

---------- ----------- --------------------

a          1           a1--a的第一个值

b          1           b1--b的第一个值



(2 行受影响)

*/

--在sql server 2005中可以使用row_number函数，不需要使用临时表。

--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',    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('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



select m.name,m.val,m.memo from

(

  select * , px = row_number() over(order by name , val) from tb

) m where px = (select min(px) from

(

  select * , px = row_number() over(order by name , val) from tb

) n where n.name = m.name)



drop table tb



/*

name       val         memo

---------- ----------- --------------------

a          1           a1--a的第一个值

b          1           b1--b的第一个值



(2 行受影响)

*/

declare @testb table(t1 int,t2 varchar(10),t3 int,t4 varchar(10),t5 int,t6 int)

insert into @testb values(11,'22',33,'44',55,66)

insert into @testb values(11,'as',33,'gr',55,66)

insert into @testb values(22,'22',33,'44',58,84) 

insert into @testb values(12,'54',33,'44',55,48) 



select * from @testb

select * from @testb a

where not exists(select 1 from @testb b where a.t3= b.t3 and a.t4 = b.t4 and a.t5 = b.t5 and a.t6<b.t6)

select * from [Table] a where not exists(select 1 from [Table] where t3=a.t3 and t4=a.t4 and t5=a.t5 and checksum(t1,t2)>checksum(a.t1,a.t2))