Looping column data insert into SQL Server database

Question

I am new to C#. My problem is I want to insert the ean, description, bookcode, price and discount into SQL Server with the qty from column 7 and above:

 

My current code is able to insert the data but the quantity is already defined. I am thinking to do looping, but I got an error "Must declare scalar variable" and I'm not sure my logic is correct.

 

Here's a screenshot of my SQL Server table: 

 

 

 

My code:

private void button3_Click(object sender, EventArgs e) {
   using (SqlConnection conn = new SqlConnection(";Trusted_Connection=False"))
   using (SqlCommand comm = new SqlCommand())
{
   comm.Connection = conn;
   conn.Open();
   for (int i = 1; i < dataGridView2.Rows.Count; i++) {
      comm.CommandText = "INSERT INTO SOLine (CustID,Bookcode,Barcode,Description,Price,Disc,Qty) VALUES ('2058 KBC',@bookcode,@barcode,@desc,@price,@disc,@qty)";
      SqlParameter bookcode = comm.Parameters.AddWithValue("@bookcode", dataGridView2.Rows[i].Cells["BOOKCODE"].Value);
      SqlParameter barcode = comm.Parameters.AddWithValue("@barcode", dataGridView2.Rows[i].Cells["3"].Value);
      SqlParameter desc = comm.Parameters.AddWithValue("@desc", dataGridView2.Rows[i].Cells["4"].Value);
      SqlParameter price = comm.Parameters.AddWithValue("@price", dataGridView2.Rows[i].Cells["5"].Value);
      SqlParameter disc = comm.Parameters.AddWithValue("@disc", dataGridView2.Rows[i].Cells["6"].Value);
      //SqlParameter qty = comm.Parameters.AddWithValue("@qty", dataGridView2.Rows[i].Cells["7"].Value);

   if (dataGridView2.Rows[i].Cells["BOOKCODE"].Value == null) { bookcode.Value = DBNull.Value; }
   if (dataGridView2.Rows[i].Cells["3"].Value == null) { barcode.Value = DBNull.Value; }
   if (dataGridView2.Rows[i].Cells["4"].Value == null) { desc.Value = DBNull.Value; }
   if (dataGridView2.Rows[i].Cells["5"].Value == null) { price.Value = DBNull.Value; }
   if (dataGridView2.Rows[i].Cells["6"].Value == null) { disc.Value = DBNull.Value; }
// if (dataGridView2.Rows[i].Cells["7"].Value == null)  // {  //       qty.Value = DBNull.Value;  // }

   for (int q = 7; q <= dataGridView2.Columns.Count; q++) //dataGridView2.Columns.Count {
      int w = 1;
      w
      w++;
      comm
      comm.Parameters.Add("@qty", SqlDbType.Int).Value = dataGridView2.Rows[w].Cells[q].Value;
      comm
      comm.Parameters.Clear();
   }                     comm.ExecuteNonQuery();
   comm
   comm.Parameters.Clear();
}
   MessageBox.Show("Save SQL");

//try
//{
//    comm.ExecuteNonQuery();
//}
//catch (Exception ex)
//{
//    MessageBox.Show(ex.ToString());
//}
}
}