mybatis实现增删改查
此文章基于我的上一篇网站,没有配置好环境的可以参考上一篇文章 juejin.cn/post/723262…
创建数据库
1、select
1.编写接口
//根据ID查询用户
User getUserById(int id);
2.编写mapper对应的sql语句
<!--根据id查询用户-->
<select id="getUserById" parameterType="int" resultType="com.lhh.pojo.User">
select * from user where id = #{id}
</select>
3.编写测试类
@Test
public void getUserById(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
User user = mapper.getUserById(1);
System.out.println(user);
2、insert
1.编写接口
//insert一个用户
int addUser(User user);
2.编写mapper对应的sql语句
<!--insert一个用户-->
<insert id="addUser" parameterType="com.lhh.pojo.User" >
insert into user (id,name,pwd) value (#{id},#{name},#{pwd})
</insert>
3.编写测试类
//insert一个用户
//增删改需要提交事务
@Test
public void addUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
int liu = mapper.addUser(new User(4, "liu", "123"));
if (liu > 0){
System.out.println("插入成功！！");
}
//提交事务
sqlSession.commit();
//关闭
sqlSession.close();
}
3、update
1.编写接口
//修改用户
int updataUser(User user);
2.编写mapper对应的sql语句
<!--修改用户-->
<update id="updataUser" parameterType="com.lhh.pojo.User">
update user set name =#{name },pwd = #{pwd} where id = #{id};
</update>
3.编写测试类
@Test
public void updataUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
mapper.updataUser(new User(4,"en","123"));
//提交事务
sqlSession.commit();
//关闭
sqlSession.close();
}
4、delete
1.编写接口
//删除用户
int deleteUser(int id);
2.编写mapper对应的sql语句
<!--删除用户-->
<delete id="deleteUser" parameterType="int">
delete from user where id = #{id};
</delete>
3.编写测试类
@Test
public void deleteUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
mapper.deleteUser(4);
//提交事务
sqlSession.commit();
//关闭
sqlSession.close();
}
