Question

这是查询

WITH dates AS (
    SELECT current_date - serie AS date
    FROM generate_series(0, 365, 1) AS serie
), items AS (
    SELECT *
    FROM items
    WHERE created_at BETWEEN now() - interval '6 months' AND now()
)

SELECT dates.date, count(items)
FROM dates
LEFT OUTER JOIN items ON items.created_at::date = dates.date
GROUP BY dates.date

除了一件事之外，一切正常 - 我需要以某种方式连续几天替换now()。因此，对于每一天，根据当天的条件计算项目计数。只是无法引用它。

有没有解决方案？

Answer 1

像这样？？

WITH dates AS (
    SELECT current_date - serie AS date
    FROM generate_series(0, 365, 1) AS serie
)
SELECT dates.date, count(items)
FROM dates
LEFT OUTER JOIN items ON created_at BETWEEN dates.date- interval '6 months' AND dates.date
GROUP BY dates.date;

Answer 2

我找到了以下解决方案，其效果与Vao Tsun提出的相同：

WITH dates AS (
    SELECT current_date - serie AS date
    FROM generate_series(0, 365, 1) AS serie
), date_intervals AS (
    SELECT
      (dates.date - INTERVAL '6 months') AS start_date,
      dates.date                         AS end_date
    FROM dates
)

SELECT date_intervals.end_date, count(items)
FROM date_intervals
  LEFT OUTER JOIN items ON items.created_at BETWEEN date_intervals.start_date AND date_intervals.end_date
GROUP BY 1
ORDER BY 1

计算按日期分组的记录，按间隔

2 个答案: