更新了上次登录字段的 C# 登录

Question

在 table 中检查用户和密码后，我尝试了几种不同的方法来更新列，尽管我没有任何运气来更新列 Last_login 有或没有 UserId (这是我的主键）除非我要将用户名更改为主键，否则我在不包含 Last_login sql 命令的情况下无法登录，尽管我更愿意包含它。

private void Connect()
        {
            SqlConnection connection = new SqlConnection();
            //Imports the methods from Custom Security class
            Custom_Security security = new Custom_Security();

            string userid = "";
            string time = "";

            try
            {
                connection.ConnectionString = connectionPath;
                connection.Open();

                SqlCommand cmd = new SqlCommand("SELECT * FROM Logins WHERE Username = @Username (UserId, Password) VALUES (@UserID, @Password)");
                cmd.CommandType = CommandType.Text;
                cmd.Connection = connection;

                cmd.Parameters.AddWithValue("@Username", txtuser.Text);
                cmd.Parameters.AddWithValue("@Password", security.AES(security.Hashstring(txtpass.Text)));
                cmd.Parameters.AddWithValue("@UserId", userid);
                cmd.ExecuteNonQuery();

                SqlDataReader dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    DialogResult dlgResult;
                    dlgResult = MessageBox.Show(
                            "Welcome: " + txtuser.Text,
                            "Login sucessful",
                            MessageBoxButtons.OK,
                            MessageBoxIcon.Information,
                            MessageBoxDefaultButton.Button1);

                    //Closes the data reader
                    dr.Close();

                    //Clears previous SQL command
                    cmd.Parameters.Clear();

                    DateTime timeNow = DateTime.UtcNow;
                    time = timeNow.ToShortTimeString();

                    //Inserts current time into field last login to update the column
                    cmd.CommandText = "INSERT INTO Logins (UserId, Last_login) VALUES (@UserId, @Last_login)";
                    cmd.Parameters.AddWithValue("@UserId", userid);
                    cmd.Parameters.AddWithValue("@Last_login",time);
                    cmd.ExecuteNonQuery();

                    this.Hide();

                    //loads the protected menu
                    Protected protectedform = new Protected(txtuser.Text);
                    protectedform.Show();
                }
                else
                {
                    DialogResult dlgResult;
                    dlgResult = MessageBox.Show(
                            "Please try again",
                            "Login unsucessful",
                            MessageBoxButtons.OK,
                            MessageBoxIcon.Warning,
                            MessageBoxDefaultButton.Button1);
                }
                connection.Close();
                connection.Dispose();                
            }
            catch (SqlException sql)
            {
                MessageBox.Show(sql.Message);
            }
        }

执行示例： http://imgur.com/88IziLt

如果有人能发现或知道解决此问题的方法，请告诉我:)。

非常感谢， 10gez10

Answer 1

您的第一个查询应该只是一个带有参数 @UserName 和 @Password

的简单 SELECT

using(SqlCommand cmd = new SqlCommand(@"SELECT * FROM Logins 
                                     WHERE Username = @Username
                                       AND Password = @Password", connection);
{
    cmd.Parameters.AddWithValue("@Username", txtuser.Text);
    cmd.Parameters.AddWithValue("@Password", security.AES(security.Hashstring(txtpass.Text)));
    using(SqlDataReader dr = cmd.ExecuteReader())
    {
         if (dr.Read())
         ....
    }
}

现在，如果您找到了您的用户，您应该使用 userid 值的更新查询来设置 lastlogin

.....
dr.Close();

//Clears previous SQL command
cmd.Parameters.Clear();

DateTime timeNow = DateTime.UtcNow;
time = timeNow.ToShortTimeString();

//Inserts current time into field last login to update the column
cmd.CommandText = @"UPDATE Logins SET Last_login
                    WHERE UserID = @UserId";
cmd.Parameters.AddWithValue("@UserId", userid);
cmd.Parameters.AddWithValue("@Last_login",time);
cmd.ExecuteNonQuery();

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