MySQL以字段进行分组并分页

• 原始数据

> SELECT * FROM `app_language`;
+----+--------+-------+--------------+--------------------------------------+---------------------+---------------------+
| id | app_id | lang  | lang_key     | lang_value                           | create_time         | update_time         |
+----+--------+-------+--------------+--------------------------------------+---------------------+---------------------+
| 1  |      1 | en-US | home.welcome | Welcome                              | 2020-05-06 08:34:44 | 2020-05-06 08:34:44 |
| 2  |      1 | zh-CN | home.hello   | 你好                                 | 2020-05-06 11:58:39 | 2020-05-06 10:32:55 |
| 3  |      1 | th-TH | home.test    | ทดสอบ                                | 2020-05-06 11:41:36 | 2020-05-06 11:32:13 |
| 4  |      1 | zh-CN | home.test    | 测试                                 | 2020-05-06 11:40:40 | 2020-05-06 11:32:13 |
| 5  |      1 | en-US | home.test    | Test                                 | 2020-05-06 11:40:45 | 2020-05-06 11:32:13 |
| 6  |      1 | th-TH | home.welcome | ยินดีต้อนรับ                         | 2020-05-06 11:41:23 | 2020-05-06 11:32:52 |
| 7  |      1 | th-TH | home.hello   | สวัสดี                               | 2020-05-06 11:59:05 | 2020-05-06 11:47:22 |
| 8  |      1 | zh-CN | home.welcome | 欢迎                                 | 2020-05-06 11:48:55 | 2020-05-06 11:47:22 |
| 9  |      1 | en-US | home.hello   | Hello                                | 2020-05-06 11:59:14 | 2020-05-06 11:47:22 |
+----+--------+-------+--------------+--------------------------------------+---------------------+---------------------+
9 rows in set (0.00 sec)

• 以lang_key进行分组（不损失数据，直接group by会损失数据，拼接的数据可在代码中处理）

mysql> select GROUP_CONCAT(lang) as lang, GROUP_CONCAT(lang_value) as lang_value, lang_key, create_time from app_language where app_id = 1 group by lang_key order by create_time desc;
+-------------------+-----------------------------------------------------+--------------+---------------------+
| lang              | lang_value                                          | lang_key     | create_time         |
+-------------------+-----------------------------------------------------+--------------+---------------------+
| zh-CN,th-TH,en-US | 你好,สวัสดี,Hello                                   | home.hello   | 2020-05-06 11:58:39 |
| th-TH,zh-CN,en-US | ทดสอบ,测试,Test                                     | home.test    | 2020-05-06 11:41:36 |
| en-US,th-TH,zh-CN | Welcome,ยินดีต้อนรับ,欢迎                           | home.welcome | 2020-05-06 08:34:44 |
+-------------------+-----------------------------------------------------+--------------+---------------------+
3 rows in set (0.01 sec)

• 以lang_key进行分组，并分页

mysql> select GROUP_CONCAT(lang) as lang, GROUP_CONCAT(lang_value) as lang_value, lang_key, create_time from app_language where app_id = 1 group by lang_key order by create_time desc limit 0,2;
+-------------------+---------------------------------+------------+---------------------+
| lang              | lang_value                      | lang_key   | create_time         |
+-------------------+---------------------------------+------------+---------------------+
| zh-CN,th-TH,en-US | 你好,สวัสดี,Hello               | home.hello | 2020-05-06 11:58:39 |
| th-TH,zh-CN,en-US | ทดสอบ,测试,Test                 | home.test  | 2020-05-06 11:41:36 |
+-------------------+---------------------------------+------------+---------------------+
2 rows in set (0.01 sec)