[Java知识库]（java）使用Mybatis-Plus中执行sql的一些常用语句

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class TestSpringMP {
    @Autowired
    private UserMapper userMapper;


    /**
     * 查询所有
     */
    @Test
    public void testSelectList() {
        List<User> users = this.userMapper.selectList(null);
           for (User user : users)
            System.out.println(user);
    }

    /**
     * 查询一个
     */
    @Test
    public void testSelectById() {
        User user = userMapper.selectById(7L);
        System.out.println(user);
    }
    /**
     * 查询多个
     */
    @Test
    public void testSelectByIds() {
        List<User> users = userMapper.selectBatchIds(Arrays.asList(1L, 2L));
        for (User user : users) {
            System.out.println(user);
        }

    }
    /**
     * 查询根据条件
     */
    @Test
    public void testSelectByConditions() {
        User user = new User();
        user.setAge(20);
        QueryWrapper<User> wrapper = new QueryWrapper<>(user);
        User user1 = userMapper.selectOne(wrapper);
        System.out.println(user1);
    }

    /**
     * 查询数据的条数
     */
    @Test
    public void testSelectCount() {
//        QueryWrapper<Object> wrapper = new QueryWrapper<>();
        Integer count = userMapper.selectCount(null);
        System.out.println(count);
    }

    /**
     * 查询集合
     */
    @Test
    public void testSelectLists() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
          wrapper.like("email","cn");
        List<User> users = userMapper.selectList(wrapper);
        for (User user : users) {
            System.out.println(user);
        }
    }

    /**
     * 查询页数
     */
    @Test
    public void testSelectPages() {
      /*  QueryWrapper<User> wrapper = new QueryWrapper<User>();
        wrapper.gt("age", 20); //年龄大于20岁*/
        Page<User> page = new Page<>(1,3);
        IPage<User> iPage = userMapper.selectPage(page, null);
        System.out.println("总记录数:"+iPage.getTotal());
        System.out.println("总页数:"+iPage.getPages());
        List<User> users = iPage.getRecords();
        for (User user : users) {
            System.out.println(user);
        }

    }
 
    /**
     * 插入
     */
    @Test
    public void testInsert() {
        User user = new User();
        user.setAge(20);
        user.setMail("test@itcast.cn");
        user.setName("曹操");
        user.setUserName("caocao");
        user.setPassword("123456");
        int result = userMapper.insert(user);
        System.out.println("数据库受影响的行数:"+result);//数据库受影响的行数
        System.out.println("id:"+user.getId());

    }

    /**
     * 根据id更新
     */
    @Test
    public void testUpdate() {
        User user = new User();
        user.setAge(18);
        user.setMail("test@itcast.cn");
        user.setName("小牛");
        user.setUserName("xiaoniu");
        user.setPassword("123456");
        user.setId(7L);
         userMapper.updateById(user);


    }
    /**
     * 根据条件更新
     */
    @Test
    public void testUpdateByConditions() {
        User user = new User();
        user.setAge(20);
        user.setName("小牛1");
        user.setUserName("xiaoniu667");
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name","小牛"); //字段的名字
        userMapper.update(user,wrapper);


    }

    /**
     * 根据条件更新1
     */
    @Test
    public void testUpdateByConditions1() {
        UpdateWrapper<User> wrapper = new UpdateWrapper<>();
        wrapper.eq("name", "小牛1").set("age", 21);/*满足名字为小牛1，修改他的年龄为21*/
        userMapper.update(null, wrapper);

    }

    /**
     * 删除操作根据id
     */
    @Test
    public void testDelete() {
       this.userMapper.deleteById(6L);
    }

    /**
     * 删除操作根据条件
     */
    @Test
    public void testDeleteByConditions() {
        HashMap<String, Object> map = new HashMap<>();
         map.put("name","小牛1");
        this.userMapper.deleteByMap(map);

    }

    /**
     * 删除操作根据条件1
     */
    @Test
    public void testDeleteByConditions1() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name","张三");
        userMapper.delete(wrapper);

    }
    /**
     * 删除操作根据条件2
     */
    @Test
    public void testDeleteByConditions2() {
        User user = new User();
        user.setAge(20);
        user.setName("李四");
        QueryWrapper<User> wrapper = new QueryWrapper<>(user);
        userMapper.delete(wrapper);

    }
    /**
     * 删除操作根据Ids
     */
    @Test
    public void testDeleteByIds() {
      userMapper.deleteBatchIds(Arrays.asList(3L,4L));
    }




}