ASP.NET C# Must declare the scalar variable

Question

I am trying to populate a GridView using a method called PopulateGrid() (below) but keep getting the same server error "Must Declare the scalar variable "@QUALID&q

Answer 1

String val = TextBox2.Text;

String sql = "SELECT QLEVELNAME FROM Qual_Levels WHERE QUALID=@QUALID";
SqlCommand cmd = new SqlCommand(sql, new SqlConnection(ConfigurationManager.ConnectionStrings["RecruitmentDBConnString"].ConnectionString));
SqlDataAdapter da = new SqlDataAdapter(sql, cmd.Connection);
DataSet ds = new DataSet();
cmd.Parameters.Add(new SqlParameter("@QUALID", val));

da.SelectCommand = cmd;
cmd.Connection.Open();

da.Fill(ds, "Qual_Levels");


SelectionGrid.DataSource = ds;
SelectionGrid.DataBind();

ds.Dispose();
da.Dispose();
cmd.Connection.Close();
cmd.Connection.Dispose();

use dis one it will work...(da.selectcommand = cmd;)