测试 update 以及 delete方法

为什么会 测试update 。控制台输出

Hibernate: 

    select

        students0_.SID as SID1_0_0_,

        students0_.SNAME as SNAME2_0_0_,

        students0_.GENDER as GENDER3_0_0_,

        students0_.BIRTHDAY as BIRTHDAY4_0_0_,

        students0_.POSTCODE as POSTCODE5_0_0_,

        students0_.PHONE as PHONE6_0_0_,

        students0_.ADDRESS as ADDRESS7_0_0_ 

    from

        STUDENTS students0_ 

    where

        students0_.SID=?

Students [sid=1, sname=哈哈, gender=男, birthday=2016-12-22 14:50:08.0]

修改的是 

s.setGender("男");

 可是 数据库里却没有发生改变呢？？