将多行数以百万计

Question

数据库中，我有几百万结构行的表如下：

UserID | Date  | Points 
1  | 2016-05-01 | 240 
1  | 2016-05-02 | 500 
1  | 2016-05-03 | 650 
2  | 2016-05-01 | 122 
2  | 2016-05-02 | 159 
2  | 2016-05-03 | 290 

等等等等。

我需要找到Points之间的差异2016-05-03和2016-05-01之间的每个ID，按差异排序Points，并返回顶部~100。我的数据库包含数亿行，因此它需要快速操作。

我从哪里开始？我正在寻找group_concat，但我不确定这是否是这个用例的正确功能。

Answer 1

此查询正在工作，它不是非常快速，但可以作出。

select tbl.id as UserId, ((select t.points from tbl t where date = '2016-05-03' and t.id=tbl.id)-(select t.points from tbl t where date = '2016-05-01' and t.id=tbl.id)) as diff from tbl group by id order by diff limit 100; 

运行这一点，让我知道，如果这是需要很长时间。

Answer 2

你应该有子查询像下面

SELECT 
    user_id, 
    (select points from tbl_test where tbl_test.date_of='2016-05-03' and user_id=t1.user_id)-t1.points as difference_in_points 
FROM `tbl_test` as t1 
WHERE date_of='2016-05-01' order by difference_in_points desc 
limit 100 

Answer 3

加入表本身。

SELECT t1.user_id, t1.points - t2.points as diff 
FROM yourTable AS t1 
JOIN yourTable AS t2 ON t1.user_id = t2.user_id 
WHERE t1.date = '2016-05-03' 
AND t2.date = '2016-05-01' 
ORDER BY diff DESC 
LIMIT 100