mysql - SQL 返回搜索集和结果

Question

如何编写一个 sql 查询，以便对于每个搜索到的 id 都返回是否找到 id ？ IN 语句中搜索的每个 id 都应该有一行，指定是否在表中找到具有该 id 的记录。

查询猜测

Select [id] From table1 Where [id] IN (1, 2, 3, 4, 5)

目标结果集

ID   Found
1    yea
2    naw
3    yea
4    yea
5    naw

Answer 1

此版本不使用 IN 运算符，而是使用 union 来获取表表达式:

create table main(id int);
insert into main
select 1 union
select 3 union
select 5


select t.id,
       case when count(m.id) > 0 then 'yep' else 'nope' end as found

from 
(select 1 as id union
 select 2 as id union
 select 3 as id union
 select 4 as id union
 select 5 as id
)t

left join main m on t.id = m.id
group by t.id

输出:

id  found
1   yep
2   nope
3   yep
4   nope
5   yep