Question

我在postgres表中有以下数据：

user id     time_stamp                action

1      '2014-12-04 17:44:46+00'     sign up
1      '2015-03-26 15:06:27+00'      work out
3      '2015-02-09 11:40:25+00'      sign up

我想要的是创建第4列

根据时间戳计算用户所做的操作，如下所示：

user id   time_stamp             action    event id

1    '2014-12-04 17:44:46+00'    sign up    1-1 ( 1st action of user id 1
1    '2015-03-26 15:06:27+00'    work out   1-2 (2nd action of user id 1
3    '2015-02-09 11:40:25+00'    sign up    2-1 ( 1st actoin of user id 1

这个问题一直困扰着我几个月..真的很感激，如果有人能帮助我解决它或指导我朝着正确的方向发展..

Answer 1

您应该使用row_number()功能。假设您的表名是users：

alter table users add column event_id text;

update users t
set event_id = e_id
from (
    select *, 
        format('%s-%s', user_id, row_number() over (partition by user_id order by time_stamp)) as e_id
    from users
    order by 1, 2
    ) sub
where sub.user_id = t.user_id and sub.time_stamp = t.time_stamp;

postgres中的条件行计数器

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