Hi,
Please check your connection string , is it proper ? after that make sure your connection done successfully ? Check SELECT P_SC, P_LIT, TOT_WORK_P, MAIN_CL_P FROM Scoresheet this is proper without any typo mistake.
Use Dataset like below.
string connetionString = null;
SqlConnection connection ;
SqlDataAdapter adapter = new SqlDataAdapter();
DataSet ds = new DataSet();
connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password";
connection = new SqlConnection(connetionString);
connection.Open();
adapter.SelectCommand = new SqlCommand("Your SQL Statement Here", connection);
adapter.Fill(ds);
connection.Close();
if(ds.Tables[0] != null && ds.Tables[0].Rows.Count > 0)
{
GridView1.DataSource = ds.Tables[0];
GridView1.DataBind();
}