---一道SQL题目,向所有CSDN高手请教-------------

[cefriend]

求一SQL语句实现数据表之间的去重复项

如有一表AT 中有四个字段

a b c d 其中 a字段,b字段,c字段为联合主键
数据如下

a b c d
1 11 22 aa
1 22 22 bb
1 33 22 cc
2 11 22 dd

有另一张表AT_Temp临时表
也有四个个字段

a b c d 其中 a字段,b字段,c字段为联合主键
数据如下
a b c d
1 22 22 bb
1 22 33 ff
2 11 44 gg

请问如何实现AT_Temp表中与AT表去掉重复记录并将不重复数据插入到AT表中

我如道如果只有一个主键 a 的话用

insert into AT select * from A_Temp from a not in (select a from AT) 可以做出来，但当他有三个主键
后我在后面中 and b not in (select b from AT) ... 是不可行的，并且效率低，求一好的SQL

[gahade]

insert   into   AT   
select   *   from   A_Temp   from   a 
where not exists(select 1 from at b where a.a=at.a and a.b=at.b and a.c=at.c)

[dawugui]

select at_temp.* from at_temp where not exists(select 1 where at_temp.a = at.a and at_temp.b = at.b and at_temp.c = at.c)

[昵称被占用了]

insert   into   AT   
select   *   from   A_Temp   from   a 
where not exists(select 1 from at b where a.a=b.a and a.b=b.b and a.c=b.c)

[昵称被占用了]

修正一楼的

insert   into   AT   
select   *   from   A_Temp a
where not exists(select 1 from at b where a.a=b.a and a.b=b.b and a.c=b.c)

[昵称被占用了]

修正2楼的

select at_temp.* from at_temp where not exists(select 1 from at where at_temp.a = at.a and at_temp.b = at.b and at_temp.c = at.c)

[gahade]

insert   into   AT   
select   *   from   A_Temp   from   a 
where not exists(select 1 from at where a.a=at.a and a.b=at.b and a.c=at.c)

[firefox_1983]

SELECT 
    name, 
    classid, 
    counts, 
    classname 
FROM 
    merchant 
WHERE 
    counts in 
    ( 
    SELECT 
        max(counts) 
    FROM 
        merchant 
    GROUP BY 
        classname 
    ) 
ORDER BY 
    counts asc 

[firefox_1983]

晕,居然贴错地方了。

[zhuyx808]

你们写语句，我来接个分

[dawugui]

匆忙中漏写表,现在才发现.多谢海阔天空.

select at_temp.* from at_temp where not exists(select 1 from at where at.a = at_temp.a and at.b = at_temp.b and at.c = at_temp.c)