使用 CTE 对 FROM 子句条目的无效引用

Question

我正在尝试编写查询来生成时间段，但出现错误：

ERROR: invalid reference to FROM-clause entry for table "prop"
Hint: There is an entry for table "prop", but it cannot be referenced from this part of the query.
Position: 346

查询是：

WITH prop AS (SELECT p.stagger, p.tariff FROM core_property p WHERE p.id = 1)
SELECT day + (hour.a * INTERVAL '1 hour') AS time,
       day + (hour.b * INTERVAL '1 hour') AS timeEnd
FROM prop,
     GENERATE_SERIES(date '2022-05-18' + prop.stagger, date '2022-05-20', '1 day'::INTERVAL) day,
     (SELECT UNNEST(CASE
                        WHEN prop.tariff = 'Economy 7' THEN ARRAY [0,12,18]
                        WHEN prop.tariff = 'Economy 10' THEN ARRAY [0] END) a,
             UNNEST(CASE
                        WHEN prop.tariff = 'Economy 7' THEN ARRAY [5,13,20]
                        WHEN prop.tariff = 'Economy 10' THEN ARRAY [7] END) b) hour;

我有这个查询的一个版本，它几乎可以工作，但会生成重复项并且很丑陋：

SELECT day + p.stagger + (CASE
                              WHEN p.tariff = 'Economy 7' THEN e7.a
                              WHEN p.tariff = 'Economy 10' THEN e10.a END) * INTERVAL '1 hour' AS time,
       day + p.stagger + (CASE
                              WHEN p.tariff = 'Economy 7' THEN e7.b
                              WHEN p.tariff = 'Economy 10' THEN e10.b END) * INTERVAL '1 hour' AS timeEnd

FROM GENERATE_SERIES(date '2022-05-18', date '2022-05-20', '1 day'::INTERVAL) day,
     (SELECT UNNEST(ARRAY [0,13,20]) a, UNNEST(ARRAY [5,16,22]) b) e10,
     (SELECT UNNEST(ARRAY [0]) a, UNNEST(ARRAY [7]) b) e7,
     (SELECT p.stagger, p.tariff FROM core_property p WHERE p.id = 1) p;

当p.tariff = 'Economy 7'时，结果是这样的，但每天应该只有一个条目：

+---------------------------------+---------------------------------+
|time                             |timeend                          |
+---------------------------------+---------------------------------+
|2022-05-18 00:15:00.000000 +00:00|2022-05-18 07:15:00.000000 +00:00|
|2022-05-18 00:15:00.000000 +00:00|2022-05-18 07:15:00.000000 +00:00|
|2022-05-18 00:15:00.000000 +00:00|2022-05-18 07:15:00.000000 +00:00|
|2022-05-19 00:15:00.000000 +00:00|2022-05-19 07:15:00.000000 +00:00|
|2022-05-19 00:15:00.000000 +00:00|2022-05-19 07:15:00.000000 +00:00|
|2022-05-19 00:15:00.000000 +00:00|2022-05-19 07:15:00.000000 +00:00|
|2022-05-20 00:15:00.000000 +00:00|2022-05-20 07:15:00.000000 +00:00|
|2022-05-20 00:15:00.000000 +00:00|2022-05-20 07:15:00.000000 +00:00|
|2022-05-20 00:15:00.000000 +00:00|2022-05-20 07:15:00.000000 +00:00|
+---------------------------------+---------------------------------+

当p.tariff = 'Economy 10'那么结果是对的：

+---------------------------------+---------------------------------+
|time                             |timeend                          |
+---------------------------------+---------------------------------+
|2022-05-18 00:15:00.000000 +00:00|2022-05-18 05:15:00.000000 +00:00|
|2022-05-18 13:15:00.000000 +00:00|2022-05-18 16:15:00.000000 +00:00|
|2022-05-18 20:15:00.000000 +00:00|2022-05-18 22:15:00.000000 +00:00|
|2022-05-19 00:15:00.000000 +00:00|2022-05-19 05:15:00.000000 +00:00|
|2022-05-19 13:15:00.000000 +00:00|2022-05-19 16:15:00.000000 +00:00|
|2022-05-19 20:15:00.000000 +00:00|2022-05-19 22:15:00.000000 +00:00|
|2022-05-20 00:15:00.000000 +00:00|2022-05-20 05:15:00.000000 +00:00|
|2022-05-20 13:15:00.000000 +00:00|2022-05-20 16:15:00.000000 +00:00|
|2022-05-20 20:15:00.000000 +00:00|2022-05-20 22:15:00.000000 +00:00|
+---------------------------------+---------------------------------+

我不确定我是否真的需要 CTE，但这似乎是在 FROM 子句中使用 prop.tariff 和 prop.stagger 的唯一方法。

Answer 1

FROM/JOIN 列表中的子查询不能引用 FROM/JOIN 列表中的其他表，除非连接声明为 lateral。所以将其声明为 LATERAL.

WITH prop AS (SELECT p.stagger, p.tariff FROM core_property p WHERE p.id = 1)
SELECT day + (hour.a * INTERVAL '1 hour') AS time,
       day + (hour.b * INTERVAL '1 hour') AS timeEnd
FROM prop,
     GENERATE_SERIES(date '2022-05-18' + prop.stagger, date '2022-05-20', '1 day'::INTERVAL) day, 
     LATERAL (SELECT UNNEST(CASE
                        WHEN prop.tariff = 'Economy 7' THEN ARRAY [0,12,18]
                        WHEN prop.tariff = 'Economy 10' THEN ARRAY [0] END) a,
             UNNEST(CASE
                        WHEN prop.tariff = 'Economy 7' THEN ARRAY [5,13,20]
                        WHEN prop.tariff = 'Economy 10' THEN ARRAY [7] END) b) hour;

一个例外是 FROM/JOIN 列表中使用的裸 set-returning 函数，它被隐式地视为横向函数。这就是为什么 `generate_series(...) 不会抛出相同的错误。

使用 CTE 对 FROM 子句条目的无效引用

invalid reference to FROM-clause entry with CTE

postgresql

common-table-expression