列Firstname不能为null

本文关键字：null 不能 Firstname | 更新日期: 2023-09-27 18:21:38

it下面是我的代码。。我在平台上试过几个答案，但仍然出现了同样的错误。。有人请帮帮我！！！！提前感谢！

public bool saveRecord(string Firstname,string Lastname,string Username,string Password,string Emailadress)
{
    using (MySqlConnection connection = new MySqlConnection("Server=localhost;Port=8889;Database=SSC;Uid=root;Password=root"))
    {
        try
        {
            string Sql_Query = "INSERT INTO administrator (Firstname,Lastname,Username,Password,EmailAdress)VALUES(@Firstname,@Lastname,@Username,@Password,@EmailAdress);";
            connection.Open();
            using (MySqlCommand command = new MySqlCommand(Sql_Query, connection))
            {
                command.Parameters.AddWithValue("@Firstname", Firstname);
                command.Parameters.AddWithValue("@Lastname", Lastname);
                command.Parameters.AddWithValue("@Username", Username);
                command.Parameters.AddWithValue("@Password", Password);
                command.Parameters.AddWithValue("@EmailAdress", Emailadress);
                command.ExecuteNonQuery();
                MessageBox.Show("Inserted");
            }
            return true;
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
            return false;
        }
    }
}

测试等级。。。。。

Models model = new Models();
if (model.saveRecord(TbFisrtname.Text, TbLastname.Text,TbUsername.Text,TbPassword.Text,TbAddress.Text) == true)
{
    MessageBox.Show("Inserted");
}

列Firstname不能为null

这表示FirstName参数变量在传递到方法时为null。我建议验证你的论点：

    public bool saveRecord(string Firstname,string Lastname,string Username,string Password,string Emailadress)
    {
        if (string.IsNullOrWhiteSpace(FirstName))
           throw new ArgumentException(FirstName, "FirstName cannot be null");
        // Do the same for the other args...
        using (MySqlConnection connection = new MySqlConnection("Server=localhost;Port=8889;Database=SSC;Uid=root;Password=root"))
        {
            try
            {
                string Sql_Query = "INSERT INTO administrator (Firstname,Lastname,Username,Password,EmailAdress)VALUES(@Firstname,@Lastname,@Username,@Password,@EmailAdress);";
                connection.Open();    
                using (MySqlCommand command = new MySqlCommand(Sql_Query, connection))
                {
                    command.Parameters.AddWithValue("@Firstname", Firstname);
                    command.Parameters.AddWithValue("@Lastname", Lastname);
                    command.Parameters.AddWithValue("@Username", Username);
                    command.Parameters.AddWithValue("@Password", Password);
                    command.Parameters.AddWithValue("@EmailAdress", Emailadress);
                    command.ExecuteNonQuery();
                    MessageBox.Show("Inserted");
                }
                return true;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return false;
            }
         }
     }
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