sql 简单的语句求助！！！！！！！
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悬赏园豆：10
[待解决问题]
求助 现在有 a b c d 四个表
a 表有 a.id字段
b c d 三个也有a.id字段，但不一定三个表都有同一个a.id,可能b表有 c d表没有
需求是
如何查询出 a表的id 在b c d中都没有的a.id的数据
所有回答(8)
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select * from a where a.id not in(select A.a.id from a A,b B,c C,d D where A.a.id=B.a.id and A.a.id=C.a.id and A.a.id=D.a.id)
-1
select a.id from a where a.id not in(select b.id from b union select c.id from c union select d.id from d)
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将b，c，d表的ID 并在一起，a和并集left join就行了，伪代码如下
select * from a left join ( b unionl c union l d ) u on a.id=u.id where u.id is null
-1
光阴的方法可行。
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SELECT *
FROM a
WHERE a.id NOT IN (
SELECT B.id FROM b B
UNION
SELECT C.id FROM c C
UNION
SELECT D.id FROM d D
)
PS：UNION表示并集，NOT IN 后面，括号内的SQL语句表示，b,c,d三个表中所有a.id的并集。
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select * from a where id not in(select id from b union select id from c union select id from d)
sql 可以直接用
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select * from b where not exists (select 1 from (select id from a where a.id=b.id))
select * from c where not exists (select 1 from (select id from a where a.id=c.id))
select * from d where not exists (select 1 from (select id from a where a.id=d.id))
找到三个表里面 A表里面都不存在的id 然后把这些ID整合 找出相同的 出来 就能查询出来
a表的id 在b c d中都不存在的a.id的数据
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select a.id from a where a.id not in(
select distinct e.id from (select b.id from b union select c.id from c union select d.id from d ) as e)