如何将 sql 参数传递给 IN()?

How to pass sqlparameter to IN()?(如何将 sql 参数传递给 IN()?)

问题描述

由于某种原因，我的 IN() 子句的 Sqlparameter 不起作用.代码编译得很好，如果我用实际值替换参数，查询就可以工作

For some reason the Sqlparameter for my IN() clause is not working. The code compiles fine, and the query works if I substitute the parameter with the actual values

StringBuilder sb = new StringBuilder();
            foreach (User user in UserList)
            {
                sb.Append(user.UserId + ",");
            }

            string userIds = sb.ToString();
            userIds = userIds.TrimEnd(new char[] { ',' });


SELECT userId, username 
FROM Users 
WHERE userId IN (@UserIds) 

推荐答案

您必须为 IN 子句中所需的每个值创建一个参数.

You have to create one parameter for each value that you want in the IN clause.

SQL 需要如下所示:

The SQL needs to look like this:

SELECT userId, username 
FROM Users 
WHERE userId IN (@UserId1, @UserId2, @UserId3, ...) 

因此您需要在 foreach 循环中创建参数和 IN 子句.
像这样的东西(在我脑海中，未经测试):

So you need to create the parameters and the IN clause in the foreach loop.
Something like this (out of my head, untested):

StringBuilder sb = new StringBuilder();
int i = 1;

foreach (User user in UserList)
{
    // IN clause
    sb.Append("@UserId" + i.ToString() + ",");

    // parameter
    YourCommand.Parameters.AddWithValue("@UserId" + i.ToString(), user.UserId);

    i++;
}

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