Codewars Postgres挑戰pg :: syntaxerror

Question

我正在Codewars.com上進行SQL挑戰。 到現在為止還挺好。

我要解決的挑戰是https://www.codewars.com/kata/calculating-month-over-month-percentage-growth-rate/train/sql

我的SQL看起來像：

select date_trunc('month', created_at)::date as date, 
  count(distinct created_at) as count, 
  100 * (count(*) - lag(count(*), 1) over (order by date)) / lag(count(*), 1) over (order by date)) || '%' as growth
from posts
group by date
order by date asc

但是，服務器不斷向我返回PG::SyntaxError: ERROR: subquery in FROM must have an alias

我不是Postgres的專家，但我知道我有日期，計數和增長方面的別名，這是該任務所期望的。

我還想念什么？

歡迎任何幫助。

Answer 1

沒關系，我發現了一個問題。 我在這一行中有一個額外的括號：

100 * (count(*) - lag(count(*), 1) over (order by date)) / lag(count(*), 1) over (order by date)) || '%' as growth

應該是：

100 * (count(*) - lag(count(*), 1) over (order by date)) / lag(count(*), 1) over (order by date) || '%' as growth