假设现在有如下N条记录 表明叫book

id author title

1 aaa AAA

2 bbb BBB

3 ccc CCC

4 ddd DDD

5 eee AAA

现在想从这5条记录中查询所有title不重复的记录

select distinct title,author from book这样是不可以的 因为distinct只能作用于一个字段

想请教应该怎么写

答案:

复制代码 代码如下:

select a.* from book a right join (

select max(id) id from book group by title) b on b.id = a.id

where a.id is not null

如果选第一条符合的记录，那么用min(id)就行了

复制代码 代码如下:

select a.* from book a right join (

select min(id) id from book group by title) b on b.id = a.id

where a.id is not null