SQLException:结果集开始之前

   ResultSet rs;
   rs = this.orderedProduct.select(" sum(unitstoproduce) "," soNo = "+ soNo);

   int sum = Integer.parseInt(rs.getString(1));

当我试图在java类中执行上述查询时,我得到一个 例外 如下所示。 这里的orderedProduct(orderedZnAlProduct)是表

   SELECT  sum(unitstoproduce)  FROM orderedZnAlProduct WHERE  soNo = '15005'

   java.sql.SQLException: Before start of result set