c# button text from sql statement

Question

I couldn't figure out why i am having problem in

btn.Text = comando.ExecuteScalar().ToString() ;

statement. If someone explains why i am having a problem( i am a newbie by the way) and how can i correct it. Thanks.

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        SqlCommand comando = new SqlCommand();
        SqlConnection conn = new SqlConnection(@"server=.\SQLEXPRESS;Initial Catalog=try;Integrated Security=True;Pooling=False");
        comando.Connection = conn;
        conn.Open();

        int NumOfButtons = 12;
        int loc = 20;
        int k = 5;
        for (int i = 1; i <= NumOfButtons; i++)
        {
            Button btn = new Button();
            ListBox lst = new ListBox();
            {
                lst.Location = new Point(4, 4);
                btn.Size = new Size(60, 20);
                btn.Tag = i;

                comando.CommandText = "select ProductName from Products where productID = " + btn.Tag;
                btn.Text = comando.ExecuteScalar().ToString() ;  // here error occurs why?
                btn.Location = new Point(k, loc);
            }

            loc += 20;

            if (i > 6)
            {
                if (loc == 160)
                {
                    loc = 20;
                }
                k = 65;
                btn.Location = new Point(k, loc);
            }
            panel1.Controls.Add(btn);
        }
    }

Answer 1

the problem was i used a character in the sql statment that is not in the English alphabets. but in my question i did not copy and paste the exact statement. thus when i corrected it, its done. but here i want to thank to all of u because i learned more from your answers. THANKS a lot. i all rated you up and just accepted devio's answer for informing more. He stated the possible problems. can be helpful for newbies like me.

Answer 2

Try this,

 ListBox lst = new ListBox();
        {
            try
            {
             lst.Location = new Point(4, 4);
             btn.Size = new Size(60, 20);
             btn.Tag = i;

             comando.CommandText = "select ProductName from Products where productID = " + btn.Tag;
             btn.Text = comando.ExecuteScalar().ToString() ;  // here error occurs why?
             btn.Location = new Point(k, loc);
            }
            catch(Exception ex)
            {
             MessageBox.Show(ex.Message);
            }
        }

now execute you app to see what your app have to say regarding the exception.

Answer 3

We don't know what kind of exception you get, so it might be any of

• there is no table Products
• the table Products does not have the columns ProductName or productId
• the Products table is missing at least one record with productID's 1 to 12.
• the ProductName column is NULL for one of the selected records