在 SQLITE 中使用窗口函数 [英] Working with window function in SQLITE

问题描述

我有这组数据

purchasingid          date   supplierid
1                2014-01-01    12
2                2014-01-01    13
3                2013-12-06    12
4                2013-12-05    11
5                2014-01-01    17
6                2013-12-05    12

我想查看所有在 2014-01-01 购买的供应商，他们之前的订单日期是什么时候.如果它不存在，则将其留空.

I want to check for all suppliers who bought on 2014-01-01 what was the date of their previous order. If it doesn't exists leave it blank.

意思是我想得到:

supplierid   date   last_time_buy_date
12            2014-01-01   2013-12-06
13            2014-01-01  
17            2014-01-01

supplierid 11 没有在 2014-01-01 购买所以他根本没有出现.

supplierid 11 did not buy on 2014-01-01 so he does not appear at all.

这就是我所做的:

select supplierid,date, max(date)
from purchasing 
where supplierid in (select supplierid
                     from purchasing
                     where date='2014-01-01')

这不起作用.我知道我应该以某种方式使用窗口函数，但我不知道如何...有什么想法吗?

This doesnt work. I know I should use window function somehow but I don't know how to... Any thoughts?

推荐答案

SQLite 不支持窗口函数.相反，您可以这样做:

SQLite doesn't support window functions. Instead, you can do:

select p.*,
       (select max(p2.date)
        from purchasing p2
        where p2.supplierid = p.supplierid and
              p2.date < p.date
       ) as prev_date
from purchasing p
where p.date = '2014-01-01';

这篇关于在 SQLITE 中使用窗口函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！