c# - C# 链接到 SQL Server Express 的错误输出

Question

下面是我按下按钮后得到的输出，尽管 EmployeeNumber 和 DOB 确实存在于我的 SQL Server 数据库中。

我已经尝试了很多次，但无法找出导致错误输出的问题。

感谢您的帮助!

C#代码:

private void btn_Click(object sender, EventArgs e)
{
    string constring = ConfigurationManager.ConnectionStrings["FirstConnection"].ConnectionString;

    SqlConnection con = new SqlConnection(constring);

    SqlCommand cmd = new SqlCommand("spEmployeeC", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.AddWithValue("@Employee", txtEmployee.Text);
    cmd.Parameters.AddWithValue("@DOB", txtPassword.Text);

    //cmd.IsValid

    con.Open();

    cmd.ExecuteNonQuery();

    if (txtEmployee.Text == "@Employee" && txtPassword.Text == "@DOB")
    {
        MessageBox.Show("Welcome " + txtEmployee.Text);
    }
    else
    {
        MessageBox.Show("The Username or Password you entered is incorrect. Please try again");
    }
}

SQL Server 存储过程代码:

CREATE PROCEDURE spEmployeeC
    @Employee INT,
    @DOB DATE
AS
BEGIN
    SET NOCOUNT ON; 

    DECLARE @Employee_check INT;
    DECLARE @Password_check DATE;

    SELECT * 
    FROM Employee_Table 
    WHERE [EMPLOYEE_NUM] = @Employee AND [DOB] = @DOB
END

Answer 1

像这样会更好:

    protected void btn_Click(object sender, EventArgs e)
    {
        if (string.IsNullOrEmpty(txtEmployee.Text))
        {
            MessageBox.Show("You must supply an Employee Number");
            return;
        }

        if (string.IsNullOrEmpty(txtPassword.Text))
        {
            MessageBox.Show("You must supply a Password");
            return;
        }

        if (IsAuthenticated())
        {
            MessageBox.Show("Welcome " + txtEmployee.Text);
        }
        else
        {
            MessageBox.Show("The Username or Password you entered is incorrect. Please try again");
        };
    }

    private bool IsAuthenticated()
    {
        using (var conn = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
        {
            SqlCommand cmd = new SqlCommand("spValidateCredentials", conn);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.Add("@Employee", SqlDbType.Int).Value = txtEmployee.Text;
            cmd.Parameters.Add("@DOB", SqlDbType.Date).Value = DateTime.Parse(txtPassword.Text);
            conn.Open();
            return ((int)cmd.ExecuteScalar() > 0);
        }
    }

也可以更改存储过程以返回记录数:

CREATE PROCEDURE [dbo].[spValidateCredentials]
    @Employee INT,
    @DOB DATE
AS 
BEGIN 
    SELECT COUNT(*) 
      FROM Employee_Table 
     WHERE EMPLOYEE_NUM=@Employee 
       AND DOB=@DOB
END