如何使用Linq To Sql从数据库调用数据到Texbox [英] How Will I Call Data To Texboxes From Database Using Linq To Sql

问题描述

我有这个，没有错误但它不起作用

i have this, no error but it doesn't work

POSDataContext pos = new POSDataContext();
Credential c = new Credential();

var q = from m in pos.Credentials where c.UserName == usernamelabel.Text select m;

fnamelabel.Text = c.FirstName;
lnamelabel.Text = c.LastName;
pnumberlabel.Text = c.PhoneNumber;
dateofcreationlabel.Text = c.DateCreated.ToString();
privilegelabel.Text = c.Privilege;

推荐答案

查看你的Linq查询：

Take a look at your Linq query:

var q = from m in pos.Credentials where c.UserName == usernamelabel.Text select m;

c 在那里做什么？



我想 q 会返回 IEnumerable< Credential> 。因此，您必须遍历Credential集合才能使用其属性：

What c is doing there?

I guess that q returns a IEnumerable<Credential>. So, you have to loop through the collection of Credential to be able to use its properties:

foreach(Credential c in q)
{
   Console.WriteLine("{0}", c.FirstName);
}

但是......如果你想要退回单个物品，试试这个：

But... if you would like to return single object, try this:

var q = pos.Credentials.Where(c=>c.UserName == "User1").SingleOrDefault();

然后：

then:

fnamelabel.Text = q.FirstName

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