public void Ycxt(string ex)
    {
        OracleConnection conn = new OracleConnection(ConnectionString);
        string sql = "select * from table_journal where xinxi='"+ ex.ToString().Trim() +"'";
        OracleDataAdapter da = new OracleDataAdapter(sql,conn);
        DataSet ds = new DataSet();
        da.Fill(ds);
    }

try
        {

        }
        catch (Exception ex)
        {
            helper log = new helper();
            log.Ycxt(ex.ToString());//这里怎样判断是否查询到了数据
        }