返回主键代码

之前insert测试中的new User()我们没给id我们来输出看一下

@Test
public void testInsertUsers() throws ParseException {
    Users users = new Users("李明", sf.parse("2001-02-05"), "1", "大兴");
    int num = uMapper.insertUsers(users);
    System.out.println(num);
    sqlSession.commit();
    System.out.println(users);
}

Users{id=null, userName='李明', birthday=Mon Feb 05 00:00:00 CST 2001, sex='1', address='大兴'}

当然，你要重写写Users.java中的toString()

<insert id="insertUsers" parameterType="users">
<selectKey keyProperty="id" resultType="int" order="BEFORE">
    select last_insert_id()
</selectKey>
    insert into users(username,birthday,sex,address) values(#{userName},#{birthday},#{sex},#{address})
</insert>

再来添加一条数据

@Test
public void testInsertUsers() throws ParseException {
    Users users = new Users("小明", sf.parse("2001-02-05"), "1", "大兴");
    int num = uMapper.insertUsers(users);
    System.out.println(num);
    sqlSession.commit();
    System.out.println(users);
}

Users{id=0, userName='小明', birthday=Mon Feb 05 00:00:00 CST 2001, sex='1', address='大兴'}

<insert id="insertUsers" parameterType="users">
<selectKey keyProperty="id" resultType="int" order="AFTER">
    select last_insert_id()
</selectKey>
    insert into users(username,birthday,sex,address) values(#{userName},#{birthday},#{sex},#{address})
</insert>

@Test
public void testInsertUsers() throws ParseException {
    Users users = new Users("小明1", sf.parse("2001-02-05"), "1", "大兴");
    int num = uMapper.insertUsers(users);
    System.out.println(num);
    sqlSession.commit();
    System.out.println(users);
}

Users{id=33, userName='小明1', birthday=Mon Feb 05 00:00:00 CST 2001, sex='1', address='大兴'}

**selectKey**标签的参数详解

• keyProperty： Users对象的哪个属性来接返回的主键值
• resultType: 返回的主键类型
• order: 在插入语句执行前，还是执行后返回主键的值