GROUP_CONCAT - WHERE条件

Question

select group_concat(bookgenre), author_authorID
from Written
group by author_authorID;

给了我

表

group_conat(bookgenre)      author_authorID
Fiction                     123450
Fiction, History            123451
History                     123457
Sci-Fi                      123458
Fiction                     123459

我不知道如何只生成

group_concat(bookgenre)     author_authorID
Fiction                     123450
Fiction                     123459

当我添加条件

时

where "group_concat(bookgenre)" like 'Fiction'

结果返回0行

Answer 1

Group_concat是一个聚合函数，因此您应该使用having而不是where来过滤 对于喜欢你应该使用wildchar %

select group_concat(bookgenre), author_authorID
from Written
group by author_authorID;
havine group_concat(bookgenre) LIKE '%fiction%'

Answer 2

你可以通过

这样做

select group_concat(bookgenre), author_authorID
from Written
group by author_authorID;
having count(*) = sum(bookgenre = 'Fiction')

或使用having子句来过滤聚合函数的结果

select group_concat(bookgenre), author_authorID
from Written
group by author_authorID;
having group_concat(bookgenre) = 'Fiction'