当在主查询中找到记录时,下面的 MYSQL 查询为我提供了我需要的输出,例如
返回:
username | total_favs
this_user | 4
但是如果在主查询中没有找到任何记录,我什么也得不到。我想得到这样的东西:
返回:
username | total_favs
null | 4
SELECT
c.username,
(SELECT COUNT(*) AS total_records FROM favourites f WHERE f.pic_id = 177) AS `total_favs`
FROM
comments c
WHERE
c.pic_id = 177