MySQL中group by max如何提取最大的一条记录

tab_game

mysql> select * from tab_game;
+----+-----------+-----------+-----------------+
| id | game_code | game_name | game_desc       |
+----+-----------+-----------+-----------------+
|  1 | 1001      | doudizhu  | doudizhuhaowan  |
|  2 | 1002      | majiang   | cuomajiangbucuo |
|  3 | 1003      | fahongbao | hongbaoxiangyao |
+----+-----------+-----------+-----------------+

tab_game_version

mysql> select * from tab_game_version;
+----+-----------+------------------+-----------+
| id | game_code | game_version_int | game_size |
+----+-----------+------------------+-----------+
|  1 | 1001      |               11 | 5MB       |
|  2 | 1001      |               12 | 6MB       |
|  3 | 1001      |               15 | 8MB       |
|  4 | 1002      |               10 | 1MB       |
|  5 | 1002      |               20 | 2MB       |
|  6 | 1003      |             1000 | 7MB       |
|  7 | 1003      |             2000 | 9MB       |
+----+-----------+------------------+-----------+

 有这样的两张表，要查出每个游戏的最大的game_version_int值的记录 

 最终想得到的结果是

game_code   game_name  game_version_int game_size
1001        斗地主         15               8MB
1002        搓麻将         20               2MB 
1003        发送包         2000             9MB

SQL 实现

第一种方式   不通用，只在MYSQL中可以用

mysql>  select game_code,max(game_version_int),game_size
    -> select * from tab_game_version t1 order by
nt desc) t group by game_code ;
+-----------+-----------------------+-----------+
| game_code | max(game_version_int) | game_size |
+-----------+-----------------------+-----------+
| 1001      |                    15 | 8MB       |
| 1002      |                    20 | 2MB       |
| 1003      |                  2000 | 9MB       |
+-----------+-----------------------+-----------+

第二种方式，采用字符串拼接的方式，可以解决

mysql>  select * from tab_game_version where
    -> concat(game_code,game_version_int)
    -> in (select concat(game_code,max(game_version_int)) from tab_game_version
t1 group by t1.game_code )  ;
+----+-----------+------------------+-----------+
| id | game_code | game_version_int | game_size |
+----+-----------+------------------+-----------+
|  3 | 1001      |               15 | 8MB       |
|  5 | 1002      |               20 | 2MB       |
|  7 | 1003      |             2000 | 9MB       |
+----+-----------+------------------+-----------+

第三种方式,

mysql>  select a.game_code,b.game_size,a.game_version_int,c.game_name from (sele
ct game_code,max(game_version_int) game_version_int from tab_game_version group
by game_code) a
    -> left join tab_game_version b on a.game_code = b.game_code and a.game_vers
ion_int = b.game_version_int  left join tab_game c on b.game_code = c.game_code
;
+-----------+-----------+------------------+-----------+
| game_code | game_size | game_version_int | game_name |
+-----------+-----------+------------------+-----------+
| 1001      | 8MB       |               15 | doudizhu  |
| 1002      | 2MB       |               20 | majiang   |
| 1003      | 9MB       |             2000 | fahongbao |
+-----------+-----------+------------------+-----------+