如何修复“当子查询未与EXISTS一起引入时，只能在选择列表中指定一个表达式".错误? [英] How to fix "Only one expression can be specified in the select list when the subquery is not introduced with EXISTS" error?

问题描述

我正在尝试在MS SQL 2012 Express上运行以下查询:

I'm trying to run the following query on MS SQL 2012 Express:

Select (
    Select Id, Salt, Password, BannedEndDate
    from Users
    where username = '" + LoginModel.Username + "'
), (
    Select Count(*)
    From LoginFails
    where username = '" + LoginModel.Username + "'
    And IP = '" + Request.ServerVariables["REMOTE_ADDR"] + "')"
);

但是出现以下错误:

当未将EXISTS引入子查询时，在select列表中只能指定一个表达式.

Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

我该如何解决这个问题?

How can I solve this problem?

推荐答案

尝试一下:

 Select 
    Id, 
    Salt, 
    Password, 
    BannedEndDate, 
    (Select Count(*) 
        From LoginFails 
        Where username = '" + LoginModel.Username + "' And IP = '" + Request.ServerVariables["REMOTE_ADDR"] + "')
 From Users 
 Where username = '" + LoginModel.Username + "'

我强烈建议您在查询中使用参数，以避免SQL注入攻击带来的安全风险！

And I recommend you strongly to use parameters in your query to avoid security risks with sql injection attacks!

希望有帮助！

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