假设你数据库有个A表：
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ID
NAME
1
aaa
2
bbb
3
ccc
4
ddd
需求：给你几个ID，返回A表中不存在的ID 给你1,2,8,9 返回8,9.
1. 一般会这么处理：select id from A where A.ID in (1,2,8,9),然后程序处理。
2.现在用一个SQL处理：
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Sql代码
select B.id
from (select 1 as id from dual
union
select 2 as id from dual
union
select 8 as id from dual
union
select 9 as id from dual
) B
left join A
on A.id = B.id
where A.id is null;