Question

我正在开发一个需要从我的数据库中获取帖子的项目。我试图获取用户和其他用户发布的帖子，除非他们是私人的。

我的SQL查询是

SELECT . . .,COUNT(F.user_id) AS is_following FROM posts AS P INNER JOIN users AS U ON U.id = P.user_id LEFT JOIN followers AS F ON F.user_id = :userid AND F.following_id = U.id WHERE *If matches search* AND U.private = 0 OR U.id = :userid OR is_following = 1 ORDER BY. . .

我选择用户跟踪海报的位置并计算它，如果0表示他们没有跟随，1表示1结果，因此，跟随他们。此外，我正在检查私人是否为0表示该帐户是公开的。

问题是当我有is_following = 1时它会返回没有结果如果我删除它虽然它确实返回结果但不是全部。

表格

users: id|username|private|...
followers: userid|followingid
posts: id|userid|body

内容：

用户：

user1|test1|1 (This is the user running the request)
user2|test2|1
user3|test3|1

追随者：

user1|user2 (User searching follows test2)

帖子：

post1|user1|HelloWorld
post2|user2|Hello_World
post3|user3|Hello-World

预期的结果是返回post1和post2而不是post3，因为user3是私有的（private设置为true / 1）而user1没有跟随test3，但是它应该显示user2的帖子，因为user1跟随user2

Answer 1

当你有{ "data" : { "2" : 2, "-LAHu2g4g2S9UBRUSzYy" : "ada", "-LAHuvLqM-14e4tC39fr" : "0818088325", "-LAIU21b5n9JKgyi9Yct" : "2", "asd" : "asd" } }条件时它没有返回结果的原因是你试图在WHERE子句中使用MySQL不允许的别名。将is_following替换为is_following，它应该有效。

Answer 2

如果我理解正确的话。

有两种群体

private 0 表示该帐户是公开的
private 1 需要在关注者表上找到以下用户。

一个简单的方法，你可以做两个查询一个是私有 0 ，另一个是私有 1 ，然后使用UNION ALL结合这些。 / p>

SELECT * FROM 
(
  SELECT p.*
  FROM users as u 
  INNER JOIN posts AS P ON p.userid = u.id  
  WHERE u.private = 0 
  UNION ALL 
  SELECT p.*
  FROM users as u 
  INNER JOIN posts AS P ON p.userid = u.id  
  RIGHT JOIN followers AS F ON F.followingid = u.id
  WHERE u.private = 1 AND f.userid = :userid 
)t

或使用exists进行检查

SELECT p.*
FROM users as u 
INNER JOIN posts AS P ON p.userid = u.id  
WHERE u.private = 0 OR exists 
(
    SELECT 1 
    FROM followers AS F LEFT JOIN users ON F.followingid = users.id
    WHERE u.id = users.id 
    and users.private 
    and f.userid = :userid 
)

sqlfiddle：http://sqlfiddle.com/#!9/50ef05/1

修改

如果你想让用户成为或不是is_following，你可以这样做。

然后您可以在外is_following子句中找到哪个用户where。

SELECT * FROM ( SELECT p.*,0 as 'is_following' FROM users as u INNER JOIN posts AS P ON p.userid = u.id WHERE u.private = 0 UNION ALL SELECT p.*,1 FROM users as u INNER JOIN posts AS P ON p.userid = u.id RIGHT JOIN followers AS F ON F.followingid = u.id WHERE u.private = 1 AND f.userid = 'user1' )t /*where is_following = 1*/

sqlfiddle：http://sqlfiddle.com/#!9/b7f6c/10

检查结果计数

2 个答案: