C# 登录系统到期日期

Question

这是我用于 C# mysql 登录系统的代码

    try
    {
        MySqlConnection connection = new MySqlConnection("Server=localhost; database=member; UID=root; Pwd=");
        MySqlCommand cmd = new MySqlCommand("SELECT * FROM member.member WHERE username='" + this.metroTextBox1.Text + "' AND password='" + this.metroTextBox2.Text + "' ;", connection);
        MySqlDataReader myReader;
        connection.Open();
        myReader = cmd.ExecuteReader();
        int count = 0;
        while (myReader.Read())
        {
            count = count + 1;
        }
        if (count == 1)
        {
            Form2 frm = new Form2();
            frm.username = metroTextBox1.Text;
            frm.Show();
            this.Visible = false;
        }
        else
        {
            MetroMessageBox.Show(this, "Incorrect login credentials. Failed to login!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }
    }

这是我的数据库 http://i.imgur.com/K831atR.png

基本上，如果过期日期已过，我想阻止登录。但我不知道该怎么办。

Answer 1

试试这个:

try
{
    MySqlConnection connection = new MySqlConnection("Server=localhost; database=member; UID=root; Pwd=");
    connection.Open();
    // Using parameters to prevent SQL Injections
    MySqlCommand cmd =
        new MySqlCommand("SELECT * FROM member.member WHERE username=@username AND password=@password ;",
            connection);
    cmd.Parameters.AddWithValue("@username", this.metroTextBox1.Text);
    cmd.Parameters.AddWithValue("@password", this.metroTextBox2.Text);

    var myReader = cmd.ExecuteReader();
    if (myReader.HasRows)
    {
        //Record found
        myReader.Read();
        // Assuming there's always a valid date in your table otherwise
        // an exception will be thrown while trying to convert to a DateTime object
        var expiryDate = myReader.GetDateTime("expirationdate");
        // Use this to show the remaining days on your label
        int remainingDays = (int) (DateTime.Now - expiryDate).TotalDays;
        string labelCaption = String.Format("You have {0} day(s) left.", remainingDays);
        if (DateTime.Now > expiryDate)
        {
            //Login Expired
        }
        else
        {
            //Login is still valid
            Form2 frm = new Form2();
            frm.username = metroTextBox1.Text;
            frm.Show();
            this.Visible = false;
        }
    }
    else
    {
        //No record found
        MetroMessageBox.Show(this, "Incorrect login credentials. Failed to login!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
    }
}
catch (Exception)
{
    // Do your exception handling
}