Mybatis练习CRUD

namespace

namespcae中的包名要和mapper接口中的方法名一致

- id:就是对应的namespace中的方法名

- resultType:　Sql语法执行的返回值

- parameter:    参数类型

1、select（选择、查询语句）

1、编写接口

List<User> getUserList();

2、编写mapper中sql语句

<select id="getUserList" resultType="com.fan.pojo.User">
    select * from mybatis.user
</select>

3、测试

@Test
public  void text(){
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    List<User> userList = mapper.getUserList();
    for(User user :userList){
        System.out.println(user);
    }
    sqlSession.close();
}

2、Insert

1、编写接口

//添加用户
int addUser(User user);

2、编写mapper中sql语句

<insert id="addUser" parameterType="com.fan.pojo.User">
    insert into mybatis.user (id,name,pwd) values(#{id},#{name},#{pwd})
</insert>

3、测试

@Test
public  void  addUser(){
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
     mapper.addUser(new User(4,"樊**","666666"));
     sqlSession.commit();
     sqlSession.close();

}

3、修改 select

1、编写接口

//修改用户
int updateUser(User user);

2、编写mapper中sql语句

<update id="updateUser" parameterType="com.fan.pojo.User">
    update mybatis.user set name=#{name},pwd=#{pwd} where id= #{id}
</update>

3、测试

@Test
public void updateUser(){
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    mapper.updateUser(new User(4,"王五","555555"));
    sqlSession.commit();
    sqlSession.close();

}

4、删除 delete

1、编写接口

//删除用户
int deleteUser(int id);

2、编写mapper中sql语句

<delete id="deleteUser" parameterType="com.fan.pojo.User">
    delete from mybatis.user where id =#{id}
</delete>

3、测试

@Test
public void  deleteUser(){
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    mapper.deleteUser(4);
    sqlSession.commit();
    sqlSession.close();


}

注意！！！
添加，删除，修改 都需要提交事务

  sqlSession.commit();
-----------------------------

如果表中字段非常多，可以用Map或者 注解
Map传递参数,直接在sql中取出key即可 【parameterType="map"】
对象传递参数，直接在sql中取出对象的属性即可 【parameterType="objiect"】
只有一个基本参数类型的情况下，可以直接在sql中取到
1、编写接口

//万能Map
int addUser2(Map<String,Object> map);

2、编写在对应的mapper中sql语句

<insert id="addUser2" parameterType="map">
    insert into mybatis.user (id,name,pwd) values(#{UserId},#{UserName},#{password})
</insert>

3、测试

@Test
public  void  addUser2(){
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    Map<String, Object> map = new HashMap<String,Object>();
    map.put("UserId",4);
    map.put("password","565656");
    map.put("UserName","樊**");
    mapper.addUser2(map);
    sqlSession.commit();
    sqlSession.close();

}