我有一个事件表(id 用作事件 ID)，如下所示(另请参阅 SQL fiddle here ):
CREATE TABLE ext (
key INT,
id CHAR(1),
pid INT,
sid INT,
oid INT,
event VARCHAR(3)
);
INSERT INTO ext (key, id, pid, sid, oid, event)
VALUES
(1, 'Q', 1, 81, 20, 'tsu'),
(2, 'Q', 1, 81, 9, 'tsu'),
(3, 'Q', 1, 81, 10, 'tsu'),
(4, 'Q', 1, 81, 4, 'tsu'),
(5, 'Q', 1, 81, 15, 'tsu'),
(6, 'Q', 1, 81, 3, 'tsu'),
(7, 'Q', 1, 81, 5, 'tsu'),
(8, 'Q', 1, 81, 18, 'tsu'),
(9, 'Q', 1, 81, 2, 'tsu'),
(10, 'Q', 1, 81, 1, 'tsu'),
(11, 'Q', 1, 81, 7, 'tsu'),
(12, 'f', 2, 2, NULL, 's'),
(13, 'Z', 2, 871, NULL, 'e'),
(14, 'm', 3, 872, 2, 'pof'),
(15, 's', 3, 873, 31, 'pom'),
(16, 'R', 3, 874, 15, 'fc'),
(17, 'R', 3, 874, 1, 'fc'),
(18, 'R', 3, 874, 31, 'fc'),
(19, 'R', 3, 874, 9, 'fc'),
(20, 'R', 3, 874, 10, 'fc'),
(21, 'R', 3, 874, 4, 'fc'),
(22, 'R', 3, 874, 7, 'fc'),
(23, 'R', 3, 874, 3, 'fc'),
(24, 'R', 3, 874, 5, 'fc'),
(25, 'R', 3, 874, 18, 'fc'),
(26, 'R', 3, 874, 20, 'fc'),
(27, 'k', 3, 876, NULL, 's'),
(28, 'a', 3, 950, 31, 'rco'),
(29, 'y', 3, 1285, 7, 'pof'),
(30, 'N', 3, 1286, 22, 'pom'),
(31, 'i', 3, 1299, 1, 'fc'),
(32, 'i', 3, 1299, 5, 'fc'),
(33, 'i', 3, 1299, 3, 'fc'),
(34, 'i', 3, 1299, 20, 'fc'),
(35, 'i', 3, 1299, 4, 'fc'),
(36, 'i', 3, 1299, 9, 'fc'),
(37, 'i', 3, 1299, 10, 'fc'),
(38, 'i', 3, 1299, 22, 'fc'),
(39, 'i', 3, 1299, 15, 'fc'),
(40, 'i', 3, 1299, 18, 'fc'),
(41, 'I', 3, 1407, 9, 'pof'),
(42, 'T', 3, 1408, 19, 'pom'),
(43, 'u', 3, 1575, 4, 'pof'),
(44, 'V', 3, 1576, 30, 'pom'),
(45, 'B', 3, 2019, NULL, 'e'),
(46, 'h', 4, 60, NULL, 'e');
事件根据 pid 和 sid 列进行排序(例如，您可以分别将它们查看为天和小时，因为 pid 是更大的时间单位比 sid 因此您应该首先按 pid 排序，然后按 sid 排序以获得正确的顺序)。正如您所看到的，某些事件(event = tsu 或 event = fc)具有不止一行，因为它们引用了许多对象 (oid )，有些仅引用一个对象(作为id = m的事件)，有些仅一行，但它们实际上引用了所有先前观察到的未“死亡”的对象。它们是一些附加规则:
- 当对象遇到
pof或rco事件(如event列中所述)时，对象就死亡了 - 当对象触发
pof事件时，会有另一个对象取代标记有pom事件的对象
我需要跟踪当前事件的对象。因此，我想将 oid 为 NULL 的行与可以从先前事件推断出的所有事件对象“交叉连接”，其中通过“交叉连接”我的意思是为每个当前事件的 oid 复制带有 oid = NULL 的行。
由于文本中的逻辑可能很难理解，我准备了预期的输出(可在 SQL fiddle here 上找到):
CREATE TABLE intermediate_result (
id CHAR(1),
pid INT,
sid INT,
oid INT,
event VARCHAR(3)
);
INSERT INTO intermediate_result (id, pid, sid, oid, event)
VALUES
('Q', 1, 81, 20, 'tsu'),
('Q', 1, 81, 9, 'tsu'),
('Q', 1, 81, 10, 'tsu'),
('Q', 1, 81, 4, 'tsu'),
('Q', 1, 81, 15, 'tsu'),
('Q', 1, 81, 3, 'tsu'),
('Q', 1, 81, 5, 'tsu'),
('Q', 1, 81, 18, 'tsu'),
('Q', 1, 81, 2, 'tsu'),
('Q', 1, 81, 1, 'tsu'),
('Q', 1, 81, 7, 'tsu'),
('f', 2, 2, 20, 's'),
('f', 2, 2, 9, 's'),
('f', 2, 2, 10, 's'),
('f', 2, 2, 4, 's'),
('f', 2, 2, 15, 's'),
('f', 2, 2, 3, 's'),
('f', 2, 2, 5, 's'),
('f', 2, 2, 18, 's'),
('f', 2, 2, 2, 's'),
('f', 2, 2, 1, 's'),
('f', 2, 2, 7, 's'),
('Z', 2, 871, 20, 'e'),
('Z', 2, 871, 9, 'e'),
('Z', 2, 871, 10, 'e'),
('Z', 2, 871, 4, 'e'),
('Z', 2, 871, 15, 'e'),
('Z', 2, 871, 3, 'e'),
('Z', 2, 871, 5, 'e'),
('Z', 2, 871, 18, 'e'),
('Z', 2, 871, 2, 'e'),
('Z', 2, 871, 1, 'e'),
('Z', 2, 871, 7, 'e'),
('m', 3, 872, 2, 'pof'),
('s', 3, 873, 31, 'pom'),
('R', 3, 874, 15, 'fc'),
('R', 3, 874, 1, 'fc'),
('R', 3, 874, 31, 'fc'),
('R', 3, 874, 9, 'fc'),
('R', 3, 874, 10, 'fc'),
('R', 3, 874, 4, 'fc'),
('R', 3, 874, 7, 'fc'),
('R', 3, 874, 3, 'fc'),
('R', 3, 874, 5, 'fc'),
('R', 3, 874, 18, 'fc'),
('R', 3, 874, 20, 'fc'),
('k', 3, 876, 15, 's'),
('k', 3, 876, 1, 's'),
('k', 3, 876, 31, 's'),
('k', 3, 876, 9, 's'),
('k', 3, 876, 10, 's'),
('k', 3, 876, 4, 's'),
('k', 3, 876, 7, 's'),
('k', 3, 876, 3, 's'),
('k', 3, 876, 5, 's'),
('k', 3, 876, 18, 's'),
('k', 3, 876, 20, 's'),
('a', 3, 950, 31, 'rco'),
('y', 3, 1285, 7, 'pof'),
('N', 3, 1286, 22, 'pom'),
('i', 3, 1299, 1, 'fc'),
('i', 3, 1299, 5, 'fc'),
('i', 3, 1299, 3, 'fc'),
('i', 3, 1299, 20, 'fc'),
('i', 3, 1299, 4, 'fc'),
('i', 3, 1299, 9, 'fc'),
('i', 3, 1299, 10, 'fc'),
('i', 3, 1299, 22, 'fc'),
('i', 3, 1299, 15, 'fc'),
('i', 3, 1299, 18, 'fc'),
('I', 3, 1407, 9, 'pof'),
('T', 3, 1408, 19, 'pom'),
('u', 3, 1575, 4, 'pof'),
('V', 3, 1576, 30, 'pom'),
('B', 3, 2019, 1, 'e'),
('B', 3, 2019, 5, 'e'),
('B', 3, 2019, 3, 'e'),
('B', 3, 2019, 20, 'e'),
('B', 3, 2019, 30, 'e'),
('B', 3, 2019, 19, 'e'),
('B', 3, 2019, 10, 'e'),
('B', 3, 2019, 22, 'e'),
('B', 3, 2019, 15, 'e'),
('B', 3, 2019, 18, 'e'),
('h', 4, 60, 1, 'e'),
('h', 4, 60, 5, 'e'),
('h', 4, 60, 3, 'e'),
('h', 4, 60, 20, 'e'),
('h', 4, 60, 30, 'e'),
('h', 4, 60, 19, 'e'),
('h', 4, 60, 10, 'e'),
('h', 4, 60, 22, 'e'),
('h', 4, 60, 15, 'e'),
('h', 4, 60, 18, 'e');
SQL版本是PostgreSQL 9.5。
最佳答案
仅用 SQL 来解决这个问题非常困难且效率低下。我认为你最好的选择是程序解决方案。
这是 PL/pgSQL 中的实现。
CREATE OR REPLACE FUNCTION f_expand_oid_null()
RETURNS TABLE(_id CHAR(1), _pid int, _sid int, _oid int, _event varchar(3))
LANGUAGE plpgsql AS
$func$
DECLARE
_key int;
_pof int; -- remember for subsequent 'pom'
BEGIN
-- hold set of "active object IDs
CREATE TEMP TABLE tmp_active_objects(
oid int PRIMARY KEY
, pid int
, sid int
, key int
) ON COMMIT DROP;
-- loop table rows in order
FOR _key, _id, _pid, _sid, _oid, _event IN
SELECT e.key, e.id, e.pid, e.sid, e.oid, e.event
FROM ext e
ORDER BY e.pid, e.sid, e.key
LOOP
IF _oid IS NULL THEN
-- expand to ordered set of active objects
RETURN QUERY
SELECT _id, _pid, _sid, a.oid, _event
FROM tmp_active_objects a
ORDER BY a.pid, a.sid, a.key; -- keep original order of events
-- returns nothing if no active objects
ELSE
RETURN QUERY VALUES (_id, _pid, _sid, _oid, _event);
CASE _event
WHEN 'rco' THEN
DELETE FROM tmp_active_objects WHERE oid = _oid;
WHEN 'pof' THEN
_pof = _oid; -- remember for subsequent 'pom'
WHEN 'pom' THEN
UPDATE tmp_active_objects
SET oid = _oid
WHERE oid = _pof;
ELSE
-- upsert active objects
INSERT INTO tmp_active_objects (oid, pid, sid, key)
VALUES (_oid, _pid, _sid, _key)
ON CONFLICT (oid) DO
UPDATE
SET (pid, sid, key)
= (EXCLUDED.pid, EXCLUDED.sid, EXCLUDED.key);
END CASE;
END IF;
END LOOP;
END
$func$;
db<> fiddle here
解释一切比编写它更费力。我做了一些假设和需要避免的陷阱。特别是，每个“pof”行后面必须紧跟一个“pom”行。
如果您对 PL/pgSQL 不坚定，请考虑付费顾问。或者以您选择的过程语言实现。
关于sql - 随着时间的推移跟踪事件对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/65815468/