你能告诉我我的实体框架查询有什么问题吗?

本文关键字：什么 问题 查询 框架 告诉我 我的 实体 | 更新日期: 2023-09-27 17:52:13

我试图在c#中选择一个成员类型的实体。我在看一个视频教程，他们做的都一样，但是对我不起作用。

        Member member = new Member();
        var query =  from m in db.Members  where Member.MemberID == textBox1.Text 
        select m;     
        var currentMember =  query.FirstOrDefault();
        string CurrentID = M.MemberID;

没有异常之类的东西，但是我得到currentMember的所有属性都是空的。有什么办法能得到预期的结果吗?

你能告诉我我的实体框架查询有什么问题吗?

我觉得你可能把变量弄混了。让我们试着整理一下这段代码:

var memberQuery = from m in db.Members
                  where m.MemberID == textBox1.Text
                     // ^ you need to reference the MemberID by the query
                     //   variable (m) not the class name (Member).
                  select m;
var member = memberQuery.SingleOrDefault();
                      // ^ when you only expect zero or one records from the
                      //   database, use SingleOrDefault instead of
                      //   FirstOrDefault, because it will throw an exception
                      //   when more than one record is returned.
if (member != null)
 // ^ always check to make sure that the database returned a value before trying
 //   to access any fields on the object.
{
    string currentId = member.MemberID;
}
else
{
    // a member with the given ID doesn't exist in the database
}

问题在where Member.MemberID == textBox1.Text

应该是where m.MemberID == textBox1.Text

为什么要创建成员?Member member = new Member();

从查询中获取Member并从中获取id

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