查询数据库中不存在的ID
假设你数据库有个A表：IDNAME1aaa2bbb3ccc4ddd
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：
select B.idfrom (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 ) Bleft join A on A.id = B.id where A.id is null;
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