在 postgresql 中获取上个月的数据
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Get data for previous month in postgresql
提问by Ilian Vasilev Kulishev
SELECT *
FROM Conference WHERE date_start ---don't know how to proceed---
How to check if date_starthas been in the previous month ? Thanks you.
如何检查是否date_start在上个月？谢谢。
回答by a_horse_with_no_name
Subtract one month from the current month, then "truncate" that to the beginning of that date. As you don't want to include rows from "this" month, you also need to add a condition for that
从当前月份减去一个月，然后将其“截断”到该日期的开头。由于您不想包含“这个”月的行，您还需要为此添加一个条件
SELECT *
FROM Conference
WHERE date_start >= date_trunc('month', current_date - interval '1' month)
and date_start < date_trunc('month', current_date)
date_trunc('month', current_date - interval '1' month)will return the 1st day of the previous month and date_trunc('month', current_date)will return the first day of "this" month.
date_trunc('month', current_date - interval '1' month)将返回上个月date_trunc('month', current_date)的第一天，并将返回“本”月的第一天。
