edit the values of a database row that are displayed in textboxes - sql

Question

New to WPF. I want to edit the values of a database row that are displayed in textboxes. At the moment I am getting an error: "ExecuteNonQuery:Connection property has not been initialized". When I remove the where clause all rows are updated and not just the selected item.
private void btnEDIT_Click(object sender, RoutedEventArgs e)
{
try
{
sc.Open();
cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'");
cmd.ExecuteNonQuery();
MessageBox.Show("Update Successfull");
sc.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Answer 1

You haven't set the Connection property of SqlCommand. So the command does not know where to connect. Use the constructor overload from SqlCommand or set it separate like this
cmd.Connection = sc;

Answer 2

cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'",sc); // add connection here
also You should use parametrized queries or Stored Procedures that will prevent SQL Injection attacks.
SqlCommand cmd = new SqlCommand("Update Rewards set Name = #name, Cost= #cost where Name = #name ,sc);
cmd.Parameters.AddWithValue("#name", Convert.ToString(this.txtName.Text)); and so on

Answer 3

I hope this is what you need :) Copy paste this. Good luck bro! :) If you have question, just ask, I'll answer if I know LOL :)
private void btnEDIT_Click(object sender, RoutedEventArgs e)
{
try
{
sc.Open();
sql = "UPDATE REWARDS SET Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'WHERE Name = '" + this.txtName.Text +"'");
SqlCommand command = new SqlCommand(sql, con);
command.ExecuteNonQuery();
MessageBox.Show("Update Successfull");
sc.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}