给定以下 MySQL 表结构:
CREATE TABLE `order_params`( `order_id` BIGINT(30) NOT NULL,
`key` VARCHAR(50) NOT NULL, `value` VARCHAR(255) NOT NULL );
还有这个数据:
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('1', 'browser', 'Firefox');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('1', 'os', 'Windows');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('2', 'browser', 'Firefox');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('2', 'os', 'Windows');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('3', 'browser', 'Firefox');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('3', 'os', 'OSX');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('4', 'browser', 'Safari');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('4', 'os', 'OSX');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('5', 'browser', 'Safari');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('5', 'os', 'OSX');
INSERT INTO `order_params` (`order_id`, `key`, `value`) VALUES ('5', 'version', '5');
如何获得以下结果?
browser Firefox os Windows 2
browser Firefox os OSX 1
browser Safari os OSX 1
browser Safari os OSX version 5 1
右边的数字是匹配唯一键/值组合的记录数。这可能吗?
好的,更新以表明我已经尝试过:
SELECT CONCAT(`key`, `value`), COUNT(*)
FROM order_params
GROUP BY `order_id`, `key`, `value`;
这是结果:
browserFirefox 1
osWindows 1
browserFirefox 1
osWindows 1
browserFirefox 1
osOS X 1
browserSafari 1
osOS X 1
我也试过这个:
SELECT `key`, `value`, COUNT(*)
FROM order_params
GROUP BY `key`, `value`;
产生这个:
browser Firefox 3
browser Safari 1
os OS X 2
os Windows 2
显然,这两个都不是想要的结果。
最佳答案
一种方法是聚合的两个阶段
select browser, os, version, count(*)
from (select order_id,
max(case when `key` = 'browser' then `value` end) as browser,
max(case when `key` = 'os' then `value` end) as os,
max(case when `key` = 'version' then `value` end) as version
from order_params op
group by order_id
) p
group by browser, os, version
如果你真的想要你拥有的字符串,你可以将它们连接在一起:
select concat(coalesce(concat('browser ', browser), ''),
coalesce(concat('os ', os), ''),
coalesce(concat('version ', version), ''), count(*)
from (select order_id,
max(case when `key` = 'browser' then `value` end) as browser,
max(case when `key` = 'os' then `value` end) as os,
max(case when `key` = 'version' then `value` end) as version
from order_params op
group by order_id
) p
group by os, browser, version
关于mysql - SQL 计算键值列的唯一组合中的行数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15711621/