要求:
A:a,b,c,d四个字段,
表中数据
aa,aa,aa,aa
bb,bb,bb,bb
cc,cc,cc,cc
dd,dd,dd,dd
B:a,b,r 三个字段
表中数据
aa,aa,a
bb,bb,b
cc,cc,c
dd,dd,b
显示结果: aa,aa,aa,aa,a
bb,bb,bb,bb,b
cc,cc,cc,cc,c
dd,dd,dd,dd,d
A:a,b,c,d四个字段,
表中数据
aa,aa,aa,aa
bb,bb,bb,bb
cc,cc,cc,cc
dd,dd,dd,dd
B:a,b,r 三个字段
表中数据
aa,aa,a
bb,bb,b
cc,cc,c
dd,dd,b
显示结果: aa,aa,aa,aa,a
bb,bb,bb,bb,b
cc,cc,cc,cc,c
dd,dd,dd,dd,d
不过下面的语句应该能达到你的效果......select A.a,A.b,A.c,A.d,B.r from A FULL JOIN B ON A.a=B.a
表中数据
aa,aa,aa,aa
bb,bb,bb,bb
cc,cc,cc,cc
dd,dd,dd,dd
B:a,b,r 三个字段
表中数据
aa,aa,a
bb,bb,b
cc,cc,c
dd,dd,b
显示结果:
aa,aa,aa,aa,a
bb,bb,bb,bb,b
cc,cc,cc,cc,c
dd,dd,dd,dd,d <---------d怎么来的?B表对应是b
select ta.a,ta.b,ta.c,ta.d,tb.r from
(
select 'aa' a,'aa' b,'aa' c,'aa' d from dual union all
select 'bb','bb','bb','bb' from dual union all
select 'cc','cc','cc','cc' from dual union all
select 'dd','dd','dd','dd' from dual
) ta
left join (
select * from
(
select 'aa' a,'aa' b,'a' r from dual union all
select 'bb','bb','b' from dual union all
select 'cc','cc','c' from dual union all
select 'dd','dd','d' from dual
) ) tb on ta.a=tb.a and ta.b=tb.b-------------------------------------
A B C D R
1 aa aa aa aa a
2 bb bb bb bb b
3 cc cc cc cc c
4 dd dd dd dd d