如何在mysql查询中解决"不在GROUP BY中"错误

Question

我有两个模型:posts并且likings具有一对多的关系(所以,一个帖子有很多喜欢).Likings模型还有一个isActive显示喜欢是主动还是被动的领域.

我想获得(排序)前5个帖子,这些帖子已经收到了最大的"活跃"喜欢(只有喜欢其isActive字段为true的帖子才会被考虑).

这是查询:

select posts.*, count(likings.id) as likes_count from 'posts'
left join 'likings' on 'likings'.'post_id' = 'posts'.'id' and 'likings'.'isActive' = 1
group by 'posts'.'id'
order by 'likes_count' desc 
limit 5

这是由这个laravel查询产生的:

Post::selectRaw('posts.*, count(likes.id) as likes_count')
    ->leftJoin('likes', function ($join) {
        $join->on('likes.post_id', '=', 'posts.id')
             ->where('likes.is_active', '=', 1);
    })
    ->groupBy('posts.id')
    ->orderBy('likes_count', 'desc')
    ->take(5)
    ->get();

这是错误:

SQLSTATE[42000]: Syntax error or access violation: 1055
'database.posts.user_id' isn't in GROUP BY

这里,posts.user_id也是posts表格的一个字段,显示了帖子的所有者.

我该如何解决这个错误？似乎改变mysql配置(可能是删除ONLY_FULL_GROUP_BY模式)是不合逻辑的,但查询中的变化最小.

Answer 1

应对每个非聚合字段进行分组.

它是标准行为,在mysql中,取决于ONLY_FULL_GROUP_BY模式.
在> =中默认启用此模式5.7.

select posts.id, post.user_id, count(likings.id) as likes_count
from posts
left join likings on likings.post_id = posts.id and likings.isActive= 1
group by posts.id, posts.user_id
order by likes_count desc 
limit 5

或者,你可以aggregate:

select posts.id, MIN(post.user_id), count(likings.id) as likes_count
from posts
left join likings on likings.post_id = posts.id and likings.isActive= 1
group by posts.id
order by likes_count desc 
limit 5

其他方式 - 改变sql_mode:

SET SESSION sql_mode = '';

此外,您可以将其分为2个查询:

1. 获取聚合和后期ID
2. 使用获取的ID获取帖子数据(带IN clause)