postgresql - 从两个时间戳创建 PostgreSQL `tsrange`

Question

我正在尝试在 postgresql 查询中创建一个 tsrange(上周四到上周四)，但出现转换错误。

这是我到目前为止所得到的(从 this SO question 开始)。

WITH past_week AS (
    SELECT date_trunc('day', NOW() + (s::TEXT || ' day')::INTERVAL)::TIMESTAMP(0) AS day 
    FROM generate_series(-7, 0, 1) AS s)
SELECT (
date_trunc('day', (SELECT day FROM past_week WHERE EXTRACT(DOW FROM day) = '4') - '7 day'::INTERVAL),
date_trunc('day', (SELECT day FROM past_week WHERE EXTRACT(DOW FROM day) = '4')));

这是结果(正确的值，但不是格式，因为它不是一个范围):

                      row                      
-----------------------------------------------
 ("2015-10-29 00:00:00","2015-11-05 00:00:00")
(1 row)

现在，有两个主要问题困扰着我:

1. 如果我尝试在查询结束前添加一个 ::tsrange，解释器会提示:

   错误:无法将类型记录转换为 tsrange 第 6 行:...ROM past_week WHERE EXTRACT(DOW FROM day) = '4')))::tsrange;

2. 我很想避免重复，但我对 SQL 不是很精通，不知道该怎么做。我们非常欢迎任何改进。

Answer 1

使用tsrange() constructor :

WITH past_week AS (
    SELECT date_trunc('day', NOW() + (s::TEXT || ' day')::INTERVAL)::TIMESTAMP(0) AS day 
    FROM generate_series(-7, 0, 1) AS s)
SELECT tsrange(
    date_trunc('day', 
        (SELECT day FROM past_week 
        WHERE EXTRACT(DOW FROM day) = '4') - '7 day'::INTERVAL),
    date_trunc('day', 
        (SELECT day FROM past_week 
        WHERE EXTRACT(DOW FROM day) = '4')));

                    tsrange                    
-----------------------------------------------
 ["2015-10-29 00:00:00","2015-11-05 00:00:00")
(1 row)

使用 CURRENT_DATE您的查询可能很简单:

WITH previous_thursday AS (
    SELECT CURRENT_DATE- EXTRACT(DOW FROM CURRENT_DATE)::int+ 4 AS thursday
    )
SELECT tsrange(thursday- '7d'::INTERVAL, thursday)
FROM previous_thursday;