left join

[好帅的一条鱼]

我不懂这个语句怎么写，把逻辑描述出来，望描述的够清楚，谢谢大家帮忙，有四个表A，B，C，D要关联
select A left join B left join C left join D 达不到效果。具体应如下：
先“表A left join 表B”--算结果1好了
在“表C left join 表D”--结果2
在将“结果1 left join 结果2”

[百年树人]

select 
  *
from
  (select * from A left join B ) result1
left join
  (select * from C left join D) result2
on
 result1.xx=result2.xx

[sdhdy]

select * from 
(select * from a left join b on 条件=...) e
left join 
(select * From c left join d on 条件=...) f  on  条件=...

[ks_reny]

[Quote=引用 1 楼 josy 的回复:]
SQL codeselect
*
from
(select * from A left join B ) result1
left join
(select * from C left join D) result2
on
result1.xx=result2.xx
[/Quote]
树人速度真快。正解。我补充一下

select 
  *
from
  (select * from A left join B on A.id=B.id ) result1
left join
  (select * from C left join D on C.id=D.id) result2
on
 result1.xx=result2.xx

[ws_hgo]

select * from (select * from A left join B ) t1
left join
(select * from C left join D) t2
on t1.xx=t2.xx