mysql - mysql中的联合和汇总

Question

当我将 header 与使用 rollup 构建的实际数据合并以将它们写入 .csv 文件时，我找不到导致此错误的原因。

CREATE TABLE `products` (
`id` int(11) default NULL,
`item` varchar(100) default NULL,
`value` int(11) default NULL
) ENGINE=MyISAM ;

INSERT INTO `products` VALUES (1,'Mobiles', '1000'),(5,'Mobiles', '2000'),(8,'Mobiles', 4000),(18,'Books',100),(28,'Books', 200),(28,'Books',400);

当我尝试下面的查询时，

 SELECT * FROM (
    (SELECT 'ITEM', 'SUM')
    UNION
    (select item, sum(value) from products group by item with rollup)
) data;

我收到这个错误

ERROR 1221 (HY000): Incorrect usage of CUBE/ROLLUP and ORDER BY

提前致谢。

Answer 1

select 'ITEM', 'SUM'
union
select item, sum(value) from products group by item with rollup
;

结果:

+---------+------+
| ITEM    | SUM  |
+---------+------+
| ITEM    | SUM  |
| Books   | 700  |
| Mobiles | 7000 |
| NULL    | 7700 |
+---------+------+