mysql - 按组对 "rollup"进行排序

Question

我发现与 group by 一起使用的“with rollup”选项非常有用。但它不适用于“order by”子句。 有什么方法可以按我想要的方式排序并计算小计吗？

CREATE TABLE `mygroup` (
  `id` int(11) default NULL,
  `country` varchar(100) default NULL
) ENGINE=MyISAM ;

INSERT INTO `mygroup` VALUES (1,'India'),(5,'India'),(8,'India'),(18,'China'),(28,'China'),(28,'China');

mysql>select country, sum(id) from mygroup group by country with rollup; 
+---------+---------+
| country | sum(id) |
+---------+---------+
| China   |      74 | 
| India   |      14 | 
| NULL    |      88 | 
+---------+---------+
3 rows in set (0.00 sec)

mysql>select country, sum(id) as cnt from mygroup group by country order by cnt ;
+---------+------+
| country | cnt  |
+---------+------+
| India   |   14 | 
| China   |   74 | 
+---------+------+
2 rows in set (0.00 sec)

mysql>select country, sum(id) as cnt from mygroup group by country with rollup order by cnt;
ERROR 1221 (HY000): Incorrect usage of CUBE/ROLLUP and ORDER BY

Expected Result:
+---------+------+
| country | cnt  |
+---------+------+
| India   |   14 | 
| China   |   74 | 
| NULL    |   88 | 
+---------+---------+
3 rows in set (0.00 sec)

Answer 1

尝试使用临时表

 SELECT * 
 FROM 
 (
     SELECT country, sum(id) as cnt 
     FROM mygroup GROUP BY country WITH rollup
 ) t 
 ORDER BY cnt;

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