Question

just got a slight problem here with updating a MySql DataGridView from visual studio in C#. The code below contains the fillData(); method that populates the datagrid. The Exception error is thrown in the button code. The aim of the button is to replace the Reviewed field from 0 to 1, meaning that the reviewed checkbox is then selected. This is probably a very basic problem so i may ask more questions, hope you can help.

public DataTable tb = new DataTable();
public MySqlDataAdapter a = new MySqlDataAdapter();

public void fillData()
{
    using (MySqlConnection c = new MySqlConnection("host="";user="";password=""; database="";"))
    {
        c.Open();                
        string strSQL = "SELECT DataID, Date, WhichMeal, HbA1C_Test, Carbohydrates, GlucoseReading, InsulinUsed, InsulinType, ReviewedBy, Reviewed From PatientData WHERE username = '" + uname.Text + "';";

        using (MySqlDataAdapter a = new MySqlDataAdapter(strSQL, c))
        {
            a.Fill(tb);
            dataGridView2.DataSource = tb;
        }


private void button5_Click(object sender, EventArgs e)
{
    using (MySqlConnection c = new MySqlConnection("host=;user=;password= ""; database=""))
    {
        try
        {
            string DataId =  dataGridView2.Rows[this.dataGridView2.SelectedRows[0].Index].Cells["DataID"].Value.ToString();
            string Update = string.Format("UPDATE PatientData SET Reviewed = 1 WHERE DataID = {0}", DataId);
            MySqlCommand command = new MySqlCommand(Update, c);

            c.Open();
            command.ExecuteNonQuery();
            c.Close();
            tb.Clear();
            fillData();
        }
        catch (MySqlException ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }
}

Answer 1

You can find the problem, by checking the following things:

• How many entries are there in
  this.dataGridView2.SelectedRows?
• How many entries are there in this.dataGridView2.Rows?
• What is the value of this.dataGridView2.SelectedRows[0].Index?

Index value is greater than the valid number of entries in one of those collecions.