3、CRUD
1、namespace
namespace中的包名要和Dao/mapper接口的包名一致
2、select
选择,查询语句
-
id:就是对应的namespace中的方法名;
-
resultType:sql语句执行的返回值!
-
paramterType:参数类型!
1.编写接口
// 查询全部用户
List<User> getUserList();
//根据ID查询用户
User getUserById(int i);
//insert一个用户
int addUser(User user);
2.编写对于的Mapper中的Sql语句
<select id="getUserById" parameterType="int" resultType="com.pireua.pojo.User">
select * from mybatis.user where id = #{id}
</select>
3.测试
@Test
public void test1(){
//第一步:获得SqlSession对象
SqlSession sqlSession = MyBatisUtils.getSqlSession();
//执行sql
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<User> userList = mapper.getUserList();
for (User user : userList){
System.out.println(user);
}
sqlSession.close();
}
注意:增删改需要提交事务
3、Inser
<!-- user中的对象可以直接取出来-->
<insert id="addUser" parameterType="com.pireua.pojo.User">
insert into mybatis.user(id,name,pwd) values (#{id},#{name},#{pwd})
</insert>
4、Update
<update id="updateUser" parameterType="com.pireua.pojo.User">
update mybatis.user set name=#{name},pwd=#{pwd} where id=#{id};
</update>
5、Delete
<delete id="deletUserById" parameterType="int">
delete from mybatis.user where id = #{id};
</delete>