Question

Hi I’m trying to get data from a local sql service database to take the input from a user register form. but when i push the button its not recorded onto the serviceable database.

do i need to use execute non query? how would i fix this code up? thanks

using System.Data.Sql;
using System.Data.SqlClient;

namespace Paddle_Power
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 form2 = new Form2();
            form2.Show();

            string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\PaddlePower.mdf;Integrated Security=True;User Instance=True";

            SqlConnection cn = new SqlConnection(connection);
            try
            {
                cn.Open();
                MessageBox.Show("open");
            }

            catch (Exception)
            {
                MessageBox.Show("Did not connect");
            }

            string username = textBox1.Text;
            string password = textBox2.Text;
            string sqlquery = ("SELECT * FROM User WHERE Username = '" + textBox1.Text + "'");
            sqlquery = "INSERT INTO [User] (Username, Password) VALUES ('" + textBox1.Text + "','" + textBox2.Text + "')";

            SqlCommand command = new SqlCommand(sqlquery, cn);

            command.Parameters.AddWithValue("Username", username);
            command.Parameters.AddWithValue("Password", password);
            command.Parameters.Clear();


        }

    }
}

Answer 1

Something along the lines of the following should hopefully do it. There’s some room for improvement, but I at least hope it solves the problem you’re having.

string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\PaddlePower.mdf;Integrated Security=True;User Instance=True";
object queryResult = null;

using (SqlConnection cn = new SqlConnection(connection))
{
    cn.Open(); // Open connection

    // SELECT
    using (SqlCommand cmd = new SqlCommand("SELECT * FROM User WHERE Username = @Username AND Password = @Password", cn))
    {
        cmd.Parameters.AddWithValue("@Username", textBox1.Text);
        cmd.Parameters.AddWithValue("@Password", textBox2.Text);

        queryResult = cmd.ExecuteScalar();
    }

    // INSERT
    using (SqlCommand cmd = new SqlCommand("INSERT INTO [User] (Username, Password) VALUES (@Username, @Password)", cn))
    {
        cmd.Parameters.AddWithValue("@Username", textBox1.Text);
        cmd.Parameters.AddWithValue("@Password", textBox2.Text);

        cmd.ExecuteNonQuery(); // or int affected = cmd.ExecuteNonQuery()
    }
}

You can requse the first SqlCommand object or create a new one. There’s very little difference with either way you choose to do it.

queryResult is just there for storing the result of cmd.ExecuteScalar(). You can map it to an object if you want (when selecting multiple columns) or cast it to a new type (if you’re selecting a single column).