MyBatis-Plus_LambdaQueryWrapper

查询专栏：建议使用LambdaQueryWrapper，防误写

/**
     * 这样写的好处防误写
     */
    @Test
    public void selectLambda() {
//    LambdaQueryWrapper<User> lambda = new QueryWrapper<User>().lambda();
//    LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
        LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();
        lambdaQuery.like(User::getName, "雨")
                .lt(User::getAge, 40);
        List<Object> userList = userMapper.selectObjs(lambdaQuery);
        userList.forEach(System.out::println);
    }

    /**
     * 5. 名字为王姓并且(年龄小于40或者邮箱不为空)
     * sql：name like '王%' and (age < 40 or email is not null)
     */
    @Test
    public void selectLambda2() {
        LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();
        lambdaQuery.likeRight(User::getName, "雨")
                .lt(User::getAge, 40)
                .isNotNull(User::getEmail);
        List<Object> userList = userMapper.selectObjs(lambdaQuery);
        userList.forEach(System.out::println);
    }

    @Test
    public void selectLambda3() {
        List<User> userList = new LambdaQueryChainWrapper<User>(userMapper)
                .like(User::getName, "雨")
                .ge(User::getAge, 20)
                .list();
        userList.forEach(System.out::println);
    }

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