技術總結記錄：hibernate使用hql查詢條件爲空

使用hibernate框架，hql語言，mysql數據庫，在做查詢的時候遇到一個問題，發現查詢的條件爲空，但是查詢總是報錯。原因是當條件爲空時，條件上應該用 is not，而不是這樣

Query query_getMoney = session1.createQuery("select sum(" + sqlField_Summation + ") from Lshsje where spNo1 = :a and spNo2 = :b and itemNo = :c");
                query_getMoney.setString("a", sp1No);
                query_getMoney.setString("b", null);
                query_getMoney.setString("c", itemNo);
                money = (double) query_getMoney.uniqueResult();

改成這樣就好了

Query query_getMoney = session1.createQuery("select sum(" + sqlField_Summation + ") from Lshsje where spNo1 = :a and spNo2 is null and itemNo = :c");
                query_getMoney.setString("a", sp1No);
                query_getMoney.setString("c", itemNo);
                money = (double) query_getMoney.uniqueResult();