满足某些条件时如何从两个不同的表中选择值

Question

我有一张桌子：

DROP TABLE TBL_A;

CREATE TABLE TBL_A
(
    number_id int, 
    country varchar(50), 
    status varchar(50), 
    number_of_days int,
    datetime date
);

INSERT INTO TBL_A
VALUES (121144, 'USA', 'CLICKED',2, '2021-10-09'),
       (121144, 'USA', 'CLAIMED',2, '2021-10-10'),
       (121144, 'USA', 'BOUGHT',2, '2021-10-11'),
       (121111, 'CAD', 'CLICKED',3, '2021-10-09'),
       (121111, 'CAD', 'CLAIMED',3, '2021-10-10'),
       (121111, 'CAD', 'BOUGHT',3, '2021-10-11'),
       (121133, 'AUS', 'CLICKED',5, '2021-10-09'),
       (121133, 'AUS', 'CLAIMED',5, '2021-10-10'),
       (121133, 'AUS', 'BOUGHT',5, '2021-10-11');

我还有一张桌子：

DROP TABLE TBL_B;

CREATE TABLE TBL_B
(
    number_id int, 
    country varchar(50), 
    status varchar(50), 
    number_of_days int,
    datetime date
);

INSERT INTO TBL_B
VALUES (121144, 'USA', 'CLICKED',6, '2021-10-20'),
       (121111, 'CAD', 'BOUGHT',10, '2021-10-21'),
       (121133, 'AUS', 'CLAIMED',5, '2021-10-02');

我想从 TBL_A 中选择所有内容，但如果在 TBL_B 中找到相同的 number_id 和 status，我只想在 datetime 较高时选择 TBL_B 中的值。

有没有办法做到这一点？在上面的示例中，只有 USA&CLICKED 和 CAD&BOUGHT 应该“更新”，因为它们在第二个表中的值具有更大的日期时间，而其余记录应该来自第一个表。

这是我目前所拥有的，但无法完成它：

select 
    number_id, 
    country, 
    status, 
    number_of_days,
    datetime date
from 
    TBL_A A
left join
    (select 
         number_id, 
         country, 
         status, 
         number_of_days,
         datetime date
     from
         TBL_B) on A.NUMBER_ID = B.NUMBER_ID 
                and a.STATUS = b.STATUS

Answer 1

此查询只为您提供结果，当 ID、Status 在两个表中并且表“TBL_B”中的日期大于表“TBL_A”中的等效日期时

SELECT
 B.*    --everything from B according to WHERE restrict
FROM
 TBL_A as A,
 TBL_B as B 
WHERE
 A.number_id = B.number_id 
 AND A.status = B.status 
 AND A.datetime < B.datetime 

当您还需要 TBL_A 的结果时，可以使用 sql 集合运算符（例如 MINUS 和 UNION）扩展此查询。

https://en.wikipedia.org/wiki/Set_operations_(SQL)

(
SELECT
 A.*    
FROM
 TBL_A as A
MINUS  --everything from "A", which is not included in "B"
SELECT
 B.*
FROM
 TBL_A as A,
 TBL_B as B 
WHERE
 A.number_id = B.number_id 
 AND A.status = B.status 
 AND A.datetime < B.datetime 
)
UNION ALL  -- Add the "B" results
SELECT
 B.*    -- everything from "B" according to WHERE restrict
FROM
 TBL_A as A,
 TBL_B as B 
WHERE
 A.number_id = B.number_id 
 AND A.status = B.status 
 AND A.datetime < B.datetime 
;