PostgreSQL中的CASE不允许使用返回集合的功能

Question

我正在尝试运行此查询，直到一段时间之前。我不知道出了什么问题，现在我开始出现此错误？

Your database returned: ERROR: set-returning functions are not allowed in CASE Hint: You might be able to move the set-returning function into a LATERAL FROM item.

我的查询：

SELECT distinct
(CASE
WHEN {PERIOD} = 'Previous Quarter' AND pto.pto_start_date < (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date AND pto.pto_end_date >= (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date
THEN generate_series(pto.pto_start_date, pto.pto_end_date, '2 day'::interval)
WHEN {PERIOD} = 'Current Quarter' AND pto.pto_start_date < (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date AND pto.pto_end_date >= (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date
THEN generate_series(pto.pto_start_date, pto.pto_end_date, '1 day'::interval)
ELSE
generate_series(pto.pto_start_date, pto.pto_end_date, '1 day'::interval)
END) AS dt
FROM cust_pto pto

开始日期和结束日期：

出了什么问题？

Answer 1

为什么现在出现错误：您已升级到postgres10。不再允许使用set返回函数。

要做的事情：有多种方法可以完成您想做的事情。为了使其尽可能接近原始查询，您要做的就是将CASE语句放在generate_series中：

SELECT distinct generate_series(
        pto.pto_start_date,
        pto.pto_end_date,
        CASE
        WHEN {PERIOD} = 'Previous Quarter' AND pto.pto_start_date < (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date AND pto.pto_end_date >= (date_trunc('quarter', now() - INTERVAL '1 month') + INTERVAL '1 month')::date THEN
            '2 day'::interval
        ELSE
            '1 day'::interval
        END
) AS dt
FROM cust_pto pto