Question

我想从数据库中的消息表中为单个用户提取消息，我写的查询有一些语法问题，但我不知道如何修复它。请帮忙

SELECT * 
FROM Messages 
WHERE SenderId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
   or ReceiverId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
   IN (SELECT * FROM Messages WHERE SenderId = 1 or ReceiverId = 1)

Answer 1

它遗漏了什么

WHERE SenderId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
or ReceiverId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
<missing expression here> IN (SELECT * FROM Messages WHERE SenderId = 1 or ReceiverId = 1)

更新可以是例如id列，如果你在messages表中

WHERE SenderId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
or ReceiverId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) 
id IN (SELECT id FROM Messages WHERE SenderId = 1 or ReceiverId = 1)

Answer 2

无需IN()搜索

SELECT * 
FROM Messages 
WHERE
    (SenderId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) and
     ReceiverId = 1) or
    (ReceiverId = (SELECT UserId FROM Users WHERE ContactNo = 03005114812 ) and
     SenderId = 1)

或者：

SELECT m.*
FROM Messages m
       INNER JOIN
     Users u
        on
             (m.SenderId = u.UserId and m.ReceiverId = 1) or
             (m.ReceiverId = u.UserId and m.SenderId = 1)
WHERE
    u.ContactNo = 03005114812

感觉它的重复次数少了一点。

Sql In子句语法查询错误

2 个答案: