项目中有这么一个需求:导入 (学生报名开发语言) excel表格时,如果数据库存在该id则可执行导入,如果不存在该语言id则提示前端,该语言id不存在!
简单一点描述就是:给你几个ID,返回language表中不存在的ID?
language表数据如下:
sql语句如下:
select B.id
from (select 1 as id from language
union
select 2 as id from language
union
select 26 as id from language
union
select 27 as id from language
) B
left join language as A
on A.id = B.id
where A.id is null;
查询结果如下: