Question

我想要一个查询，列出状态为“活动”的所有客户。此查询将返回标记为活动的客户列表。我的问题是我在查询引用其他表的表时丢失了。这是我的架构。

 CREATE TABLE Customer (
  ID BIGSERIAL PRIMARY KEY NOT NULL,
  fNAME TEXT NOT NULL,
  lNAME TEXT NOT NULL,
  create_date DATE NOT NULL DEFAULT NOW() 
 );

 CREATE TABLE CustomerStatus (
  recordID BIGSERIAL NOT NULL,
  ID BIGSERIAL REFERENCES Customer NOT NULL,
  status TEXT NOT NULL,
  create_date DATE NOT NULL DEFAULT NOW()
 );

 INSERT INTO Customer (fNAME, lNAME) VALUES ('MARK', 'JOHNSON'), ('ERICK', 'DAWN'), ('MAY', 'ERICKSON'), ('JESS', 'MARTIN');

 INSERT INTO CustomerStatus (ID, status) VALUES (1, 'pending'), (1, 'active');     

 INSERT INTO CustomerStatus (ID, status) VALUES (2, 'pending'), (2, 'active'), (2, 'cancelled');     

 INSERT INTO CustomerStatus (ID, status) VALUES (3, 'pending'), (3, 'active');  

 INSERT INTO CustomerStatus (ID, status) VALUES (4, 'pending');

Answer 1

我勇敢地假设record_id是serial =＆gt;最新的id将是最后一个，产生这个qry：

t=# with a as (
  select *, max(recordid) over (partition by cs.id)
  from Customer c
  join CustomerStatus cs on cs.id = c.id
)
select *
from a
where recordid=max and status = 'active';
 id | fname |  lname   | create_date | recordid | id | status | create_date | max
----+-------+----------+-------------+----------+----+--------+-------------+-----
  1 | MARK  | JOHNSON  | 2017-04-27  |        2 |  1 | active | 2017-04-27  |   2
  3 | MAY   | ERICKSON | 2017-04-27  |        7 |  3 | active | 2017-04-27  |   7
(2 rows)

Time: 0.450 ms

PostgreSQL通过模式查询

1 个答案: