Question

I have been following a tutorial on the internet it can be found at Add a New Record to the Database. I have code that is identical for input in to a dataset and database, but I get this error

Object reference not set to an
instance of an object.

here is my full code

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        System.Data.SqlClient.SqlConnection con;
        System.Data.SqlClient.SqlDataAdapter da;
        DataSet ds1;


        int MaxRows = 0;
        int inc = 0;

        private void Form1_Load(object sender, EventArgs e)
        {
            con = new System.Data.SqlClient.SqlConnection();
            ds1 = new DataSet();

            con.ConnectionString = "Data Source=localhost;Initial Catalog=Kart_Setup;Integrated Security=True;Pooling=False";

            con.Open();

            da.Fill(ds1, "Setup");   
        }

        private void clr_Click(object sender, EventArgs e)
        {


        }

        private void save_Click(object sender, EventArgs e)
        {
            System.Data.SqlClient.SqlCommandBuilder cb;
            cb = new System.Data.SqlClient.SqlCommandBuilder(da);


          DataRow dRow = ds1.Tables["Setup"].NewRow();

          dRow[1] = FL.Value;
          dRow[2] = FR.Value;
          dRow[3] = RL.Value;
          dRow[4] = RR.Value;

          ds1.Tables["Setup"].Rows.Add(dRow);

          MaxRows = MaxRows + 1;
          inc = MaxRows - 1;

          da.Update(ds1, "Setup");

          MessageBox.Show("Setup Added");

          con.Close();
        }
    }
}

Any help would be appreciated thanks in advance

Answer 1

You need to declare ds to something… try….

EDIT: Fixed code to add datatable to the dataset.

DataSet ds1 = new DataSet();
DataTable dt = new DataTable("Setup");
ds1.Tables.Add(dt);
DataRow dRow = ds1.Tables["Setup"].NewRow();

Also, be sure to initialize all variables, these look suspicious:

MaxRows = MaxRows + 1;
inc = MaxRows - 1;

It looks as though these are declared in the class itself, put this outside of the function:

public intMaxRows = 0;
public int inc = 0;

Also, I do not know what da is supposed to be, but you’ll need to instantiate that as well.