SQL 按时间戳排序并分配数值答案

【问题标题】：SQL Order by Timestamp and Assign Numeric ValueSQL 按时间戳排序并分配数值
【发布时间】：2015-02-04 14:58:39
【问题描述】：

我有一个活动的 cust_id 和时间戳列表。我想添加一个名为“activity_order”的列，它会给每个 cust_id 一个顺序，其中“1”被分配给最大时间戳

 cust_id | time_stamp
 ________  __________
 a1        2015-01-31 10:48:43
 a1        2015-01-31 12:48:46
 a1        2015-01-31 17:50:40
 b1        2015-01-25 10:39:01
 b1        2015-01-31 12:53:34

这就是我想要的结果：

 cust_id | time_stamp            | activity_order
 ________  ___________________    _________________
 a1        2015-01-31 10:48:43     3    
 a1        2015-01-31 12:48:46     2
 a1        2015-01-31 17:50:40     1
 b1        2015-01-25 10:39:01     2
 b1        2015-01-31 12:53:34     1

这是我的尝试，但问题是这个 CASE 语句只有这么大，我想我需要一个循环或类似的东西，以防 cust_id 有大于 2 个活动。

SELECT a.cust_id
,a.time_stamp
,CASE WHEN a.time_stamp = b.max_ts THEN 1 ELSE 2 END as activity_order
FROM ACTIVITY a
JOIN (SELECT
cust_id
,MAX(time_stamp) as max_ts
FROM activity_order) b
ON a.cust_id = b.cust_id

【问题讨论】：

标签： sql hive hql

【解决方案1】：

SELECT cust_id
, time_stamp
, RANK () OVER(PARTITION BY cust_id ORDER BY time_stamp DESC) as activity_order
FROM activity
ORDER BY cust_id ASC, activity_order DESC

工作示例：http://sqlfiddle.com/#!6/b6d85/3

【讨论】：

【解决方案2】：

尝试假设 MS SQL

Update B
Set Activity_Order = RN
From
(select CustID, [Time_stamp], Row_Number() Over(Partition By CustID Order By [Time_stamp] desc) as RN
From Activity) A
inner join Activity B on A.CustID = B.CustID and A.[Time_stamp] = B.[Timestamp]

【讨论】：

【解决方案3】：

我会给我们 Row_Number 一个分区。注意：您使用 3 个 cust_ID：a1、b1、b2。但是您的示例在 b2 下订购了 b1。这是您的示例中的错误吗？

这是我的尝试：

SELECT 
cust_id, time_stamp, 
activity_order = ROW_NUMBER() OVER (PARTITION BY cust_id ORDER BY cust_id     ASC, time_stamp DESC) 
FROM ACTIVITY

【讨论】：