postgresql generate_series 几个月 [英] Postgresql generate_series of months

问题描述

我正在尝试使用 generate_series 函数在 PostgreSQL 中生成一个系列.我需要从 2008 年 1 月到 current month + 12 (一年后)的一系列月份.我正在使用并仅限于 PostgreSQL 8.3.14(所以我在 8.4 中没有时间戳系列选项).

I'm trying to generate a series in PostgreSQL with the generate_series function. I need a series of months starting from Jan 2008 until current month + 12 (a year out). I'm using and restricted to PostgreSQL 8.3.14 (so I don't have the timestamp series options in 8.4).

我知道如何获得一系列的日子，例如:

I know how to get a series of days like:

select generate_series(0,365) + date '2008-01-01'

但我不知道该怎么做.

推荐答案

select DATE '2008-01-01' + (interval '1' month * generate_series(0,11))

编辑

如果您需要动态计算数字，以下方法可能会有所帮助:

If you need to calculate the number dynamically, the following could help:

select DATE '2008-01-01' + (interval '1' month * generate_series(0,month_count::int))
from (
   select extract(year from diff) * 12 + extract(month from diff) + 12 as month_count
   from (
     select age(current_timestamp, TIMESTAMP '2008-01-01 00:00:00') as diff 
   ) td
) t

这会计算自 2008-01-01 以来的月数，然后在其上加上 12.

This calculates the number of months since 2008-01-01 and then adds 12 on top of it.

但我同意 Scott 的观点:你应该把它放到一个集合返回函数中，这样你就可以做类似 select * from calc_months(DATE '2008-01-01')

But I agree with Scott: you should put this into a set returning function, so that you can do something like select * from calc_months(DATE '2008-01-01')

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