public static int CountByCourse(Command cmd,string courseId)
{
string table = Selection.Table;
string sql = string.Format(@"select count(*) from {0} where lower(Course_Id)=lower(@Course_Id)", table);
cmd.CommandText = sql;
cmd.AddParameter("@Course_Id", courseId);
object count = cmd.ExecuteScalar();
return (count == null || count is DBNull) ? 0 : Convert.ToInt32(count);
}