Mybatis学习笔记(四)【入门程序二】

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<!-- 添加用户
parameterType：指定输入 参数类型是pojo（包括 用户信息）
#{}中指定pojo的属性名，接收到pojo对象的属性值，mybatis通过OGNL获取对象的属性值
-->
<insert id="insertUser" parameterType="com.iot.mybatis.po.User">
<!--
将插入数据的主键返回，返回到user对象中

SELECT LAST_INSERT_ID()：得到刚insert进去记录的主键值，只适用与自增主键

keyProperty：将查询到主键值设置到parameterType指定的对象的哪个属性
order：SELECT LAST_INSERT_ID()执行顺序，相对于insert语句来说它的执行顺序
resultType：指定SELECT LAST_INSERT_ID()的结果类型
-->
<selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
SELECT LAST_INSERT_ID()
</selectKey>
INSERT INTO user (username,birthday,sex,address)values (#{username},#{birthday},#{sex},#{address})
<!--
使用mysql的uuid（）生成主键
执行过程：
首先通过uuid()得到主键，将主键设置到user对象的id属性中
其次在insert执行时，从user对象中取出id属性值
-->
<!--  <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.String">
SELECT uuid()
</selectKey>
insert into user(id,username,birthday,sex,address) value(#{id},#{username},#{birthday},#{sex},#{address}) -->

</insert>

<!-- 删除 用户
根据id删除用户，需要输入 id值
-->
<delete id="deleteUser" parameterType="java.lang.Integer">
delete from user where id=#{id}
</delete>

<!-- 根据id更新用户
分析：
需要传入用户的id
需要传入用户的更新信息
parameterType指定user对象，包括 id和更新信息，注意：id必须存在
#{id}：从输入 user对象中获取id属性值
-->
<update id="updateUser" parameterType="com.iot.mybatis.po.User">
update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address}
where id=#{id}
</update>

birthday

birthday

java.util.Date

#{modified_date,jdbcType=TIMESTAMP}、#{date,jdbcType=DATE}

birthday

#{birthday,jdbcType=TIMESTAMP}

程序代码

// 添加用户信息
@Test
public void insertUserTest() throws IOException {
// mybatis配置文件
String resource = "SqlMapConfig.xml";
// 得到配置文件流
InputStream inputStream = Resources.getResourceAsStream(resource);

// 创建会话工厂，传入mybatis的配置文件信息
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
.build(inputStream);

// 通过工厂得到SqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
// 插入用户对象
User user = new User();
user.setUsername("王小军");
user.setBirthday(new Date());
user.setSex("1");
user.setAddress("河南郑州");

sqlSession.insert("test.insertUser", user);

// 提交事务
sqlSession.commit();

// 获取用户信息主键
System.out.println(user.getId());
// 关闭会话
sqlSession.close();

}

// 根据id删除 用户信息
@Test
public void deleteUserTest() throws IOException {
// mybatis配置文件
String resource = "SqlMapConfig.xml";
// 得到配置文件流
InputStream inputStream = Resources.getResourceAsStream(resource);

// 创建会话工厂，传入mybatis的配置文件信息
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
.build(inputStream);

// 通过工厂得到SqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();

// 传入id删除 用户
sqlSession.delete("test.deleteUser", 29);

// 提交事务
sqlSession.commit();

// 关闭会话
sqlSession.close();

}

// 更新用户信息
@Test
public void updateUserTest() throws IOException {
// mybatis配置文件
String resource = "SqlMapConfig.xml";
// 得到配置文件流
InputStream inputStream = Resources.getResourceAsStream(resource);

// 创建会话工厂，传入mybatis的配置文件信息
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
.build(inputStream);

// 通过工厂得到SqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
// 更新用户信息

User user = new User();
//必须设置id
user.setId(27);
user.setUsername("王大军");
user.setBirthday(new Date());
user.setSex("2");
user.setAddress("河南郑州");

sqlSession.update("test.updateUser", user);

// 提交事务
sqlSession.commit();

// 关闭会话
sqlSession.close();

}

<selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
SELECT LAST_INSERT_ID()
</selectKey>

resultType

org.apache.ibatis.exceptions.PersistenceException:
### Error updating database.  Cause: org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'test.insertUser!selectKey'.  It's likely that neither a Result Type nor a Result Map was specified.
### The error may exist in sqlmap/User.xml
### The error may involve test.insertUser!selectKey-Inline
### The error occurred while setting parameters
### SQL: SELECT LAST_INSERT_ID()
### Cause: org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'test.insertUser!selectKey'.  It's likely that neither a Result Type nor a Result Map was specified.

...

Caused by: org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'test.insertUser!selectKey'.  It's likely that neither a Result Type nor a Result Map was specified.

总结

#{}

${}

#{}

#{}

#{}

#{}

${}

${}

${}

${}

${}

mybatis和hibernate本质区别和应用场景