登录表单的麻烦 [英] Login Form trouble

问题描述

我写了下面code在登录到使用C＃和LINQ我的应用程序。它连接到我在Visual Studio中创建的SQL面向服务的数据库。那我遇到的问题是，我不明白，我希望有人能帮助我这里。我创建了两个消息盒装试一试，看我的code买，我没有得到来自任何东西的输出。

如果有人可以帮助这将是伟大的！

 公共BOOL用户登陆（用户字符串，字符串传递）
{
    VAR数据库=新ExampleDataSet（）;

    VAR的查询=从员工的Database.Employee
        其中（Employee.EmployeeID.ToString（）== Employee.ToLower（）＆安培;＆安培; Employee.Password ==通行证）
        选择员工;

    如果（query.Count（）！= 0）
    {
        返回true;
        的MessageBox.show（您登录）;
    }

    返回false;
    的MessageBox.show（您没有登录）;
}

私人无效cmdLogin_Click（对象发件人，EventArgs的）
{
    字符串USER =（txtUser.Text）;
    字符串传递=（txtPass.Text）;
    用户登陆（用户，通行证）;
}
 

解决方案

从你写的code，似乎问题是，你比较字符串重的presentation 员工及其雇员属性 Employee.EmployeeID.ToString（）== Employee.ToLower（）。这条线将随时返回假除非覆盖的ToString（） 员工的方法类返回的财产雇员（我presume你没有）。 试试这个，而不是（假设参数用户包含了用户的姓名）：

 使用（var数据=新ExampleDataSet（））
{
    VAR的loggedIn = dataSet.Employee.Any（E =＆GT; e.UserName ==用户放大器;＆安培; e.Password ==通行证）;
    VAR消息=的loggedIn？ 您登录：您还没有登录;
    的MessageBox.show（消息）;
    返回的loggedIn;
}
 

I wrote the following code to log in to my application using C# and LINQ. It connected to a SQL service oriented database that I have created in Visual Studio. The problem that I am having is one that I do not understand and am hoping that someone can help me about here. I have created two message boxed to try to see the output of my code buy I am not getting anything from it.

If anyone could help that would be great!

public bool UserLogin(string User, string Pass)
{
    var Database = new ExampleDataSet();

    var query = from Employee in Database.Employee
        where (Employee.EmployeeID.ToString() == Employee.ToLower() && Employee.Password == Pass)
        select Employee;

    if (query.Count() != 0)
    {
        return true;
        MessageBox.Show("You are logged in");
    }

    return false;
    MessageBox.Show("You are not logged in");
}

private void cmdLogin_Click(object sender, EventArgs e)
{
    string User = (txtUser.Text);
    string Pass = (txtPass.Text);
    UserLogin(User, Pass);
}

解决方案

From the code you wrote, it seems that the problem is that you compare the string representation of an Employee with its EmployeeId property Employee.EmployeeID.ToString() == Employee.ToLower(). This line will always return false unless you override ToString() method of Employee class to return the property EmployeeId (which I presume you didn't). Try this instead (assuming that parameter User contains the name of the user):

using(var dataSet = new ExampleDataSet())
{
    var loggedIn = dataSet.Employee.Any(e=>e.UserName == User && e.Password == Pass);
    var message = loggedIn ? "You are logged in" : "You are not logged in";
    MessageBox.Show(message);
    return loggedIn;
}

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