using (SqlConnection connection = new SqlConnection(Connection_sheets))
{
    connection.Open();

    SqlCommand cmd = new SqlCommand("select distinct [Sheet Code] from cell where [Table Code] = 'Table Number' order by [Sheet Code] asc", connection);
    SqlDataReader readert = cmd.ExecuteReader();
 }

DataRow newRow2 = _longDataTable.NewRow();
newRow2.ItemArray = drlibrary.ItemArray;

newRow2["VariableTableCode"] = tableName;
newRow2["VariableRowCode"] = ssRowNoBars;
newRow2["VariableColumnCode"] = ssColumnNoBars;

_longDataTable.Rows.Add(newRow2);