mysql-group by 分页

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测试数据

CREATE TABLE `book_comment` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `user_id` int(10) unsigned NOT NULL,
  `like_num` int(10) NOT NULL DEFAULT '0' COMMENT '点赞数',
  `content` varchar(200) NOT NULL,
  `addtime` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `user_id` (`user_id`),
  KEY `addtime` (`addtime`),
  KEY `uid_addtime` (`user_id`,`addtime`)
) ENGINE=InnoDB COMMENT='书本评论表';


INSERT INTO `book_comment` VALUES ('1', '1', '0', '评论1', '2017-05-17 00:00:00');
INSERT INTO `book_comment` VALUES ('2', '1', '2', '评论2', '2017-05-17 00:03:01');
INSERT INTO `book_comment` VALUES ('3', '2', '3', '评论3', '2017-05-17 00:03:02');
INSERT INTO `book_comment` VALUES ('4', '2', '4', '评论4', '2017-05-17 00:00:03');
INSERT INTO `book_comment` VALUES ('5', '3', '0', '评论5', '2017-05-17 00:00:04');
INSERT INTO `book_comment` VALUES ('6', '1', '1', '评论6', '2017-05-17 00:00:05');
INSERT INTO `book_comment` VALUES ('7', '4', '0', '评论7', '2017-05-17 00:00:06');
INSERT INTO `book_comment` VALUES ('8', '4', '2', '评论8', '2017-05-17 00:00:07');
INSERT INTO `book_comment` VALUES ('9', '4', '0', '评论9', '2017-05-17 00:00:08');
INSERT INTO `book_comment` VALUES ('10', '4', '3', '评论10', '2017-05-17 00:00:09');
INSERT INTO `book_comment` VALUES ('11', '3', '2', '评论11', '2017-05-17 00:00:10');

CREATE TABLE `book_comment_like` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `comment_id` int(10) unsigned NOT NULL COMMENT '评论表id',
  `like_name` varchar(200) NOT NULL COMMENT '点赞用户',
  `addtime` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `comment_id` (`comment_id`),
  KEY `addtime` (`addtime`)
) ENGINE=InnoDB COMMENT='书本评论点赞表';


INSERT INTO `book_comment_like` VALUES ('1', '1', '点赞用户1', '2017-05-17 00:03:01');           
INSERT INTO `book_comment_like` VALUES ('2', '1', '点赞用户2', '2017-05-17 00:03:01');           
INSERT INTO `book_comment_like` VALUES ('3', '2', '点赞用户3', '2017-05-17 00:03:02');           
INSERT INTO `book_comment_like` VALUES ('4', '2', '点赞用户4', '2017-05-17 00:03:02');           
INSERT INTO `book_comment_like` VALUES ('5', '2', '点赞用户5', '2017-05-17 00:03:02');           
INSERT INTO `book_comment_like` VALUES ('6', '2', '点赞用户6', '2017-05-17 00:00:03');           
INSERT INTO `book_comment_like` VALUES ('7', '3', '点赞用户7', '2017-05-17 00:00:04');           
INSERT INTO `book_comment_like` VALUES ('8', '5', '点赞用户8', '2017-05-17 00:00:06');           
INSERT INTO `book_comment_like` VALUES ('9', '5', '点赞用户9', '2017-05-17 00:00:07');           
INSERT INTO `book_comment_like` VALUES ('10', '5', '点赞用户10', '2017-05-17 00:00:08');         

关联表一对多。一条评论会有多个用户点赞。

需要分页显示，根据评论表(主表)分页，并且显示点赞用户详情

1：方案一

先查评论表(根据分页要求)，然后依次遍历每条评论信息，获取对应的点赞用户

2：方案二

mysql> SELECT
    a.*, b.*
FROM
    (
        SELECT
            *
        FROM
            book_comment
        GROUP BY
            id
        LIMIT 0,
        5
    ) a
LEFT JOIN book_comment_like b ON a.id = b.comment_id;
+----+---------+----------+---------+---------------------+------+------------+------------+---------------------+
| id | user_id | like_num | content | addtime             | id   | comment_id | like_name  | addtime             |
+----+---------+----------+---------+---------------------+------+------------+------------+---------------------+
|  1 |       1 |        0 | 评论1   | 2017-05-17 00:00:00 |    1 |          1 | 点赞用户1  | 2017-05-17 00:03:01 |
|  1 |       1 |        0 | 评论1   | 2017-05-17 00:00:00 |    2 |          1 | 点赞用户2  | 2017-05-17 00:03:01 |
|  2 |       1 |        2 | 评论2   | 2017-05-17 00:03:01 |    3 |          2 | 点赞用户3  | 2017-05-17 00:03:02 |
|  2 |       1 |        2 | 评论2   | 2017-05-17 00:03:01 |    4 |          2 | 点赞用户4  | 2017-05-17 00:03:02 |
|  2 |       1 |        2 | 评论2   | 2017-05-17 00:03:01 |    5 |          2 | 点赞用户5  | 2017-05-17 00:03:02 |
|  2 |       1 |        2 | 评论2   | 2017-05-17 00:03:01 |    6 |          2 | 点赞用户6  | 2017-05-17 00:00:03 |
|  3 |       2 |        3 | 评论3   | 2017-05-17 00:03:02 |    7 |          3 | 点赞用户7  | 2017-05-17 00:00:04 |
|  5 |       3 |        0 | 评论5   | 2017-05-17 00:00:04 |    8 |          5 | 点赞用户8  | 2017-05-17 00:00:06 |
|  5 |       3 |        0 | 评论5   | 2017-05-17 00:00:04 |    9 |          5 | 点赞用户9  | 2017-05-17 00:00:07 |
|  5 |       3 |        0 | 评论5   | 2017-05-17 00:00:04 |   10 |          5 | 点赞用户10 | 2017-05-17 00:00:08 |
|  4 |       2 |        4 | 评论4   | 2017-05-17 00:00:03 | NULL | NULL       | NULL       | NULL                |
+----+---------+----------+---------+---------------------+------+------------+------------+---------------------+
11 rows in set

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