Question

我需要一个可以满足以下逻辑的查询。该逻辑是由我创建的，但我不是那种以SQL格式编写的专家。

逻辑是我们必须在客户端表中找到Y和L并复制列。客户端中只有它的N，然后我们必须在“历史记录”中搜索第一个Y并更新，或者如果“历史记录”中没有Y，则必须寻找第一个L并更新

如果有人帮助我进行修改，我将不胜感激。

client表包含最新数据，而client_h表具有相同客户端的历史记录。

 If     client.FLAG  = ‘Y’ or ‘L’ , Then 

    UPDATE client SET 
    client.FLAG_new  = client.FLAG, 
    client.DT_new = client.DT  

    ELSE 

    If client.FLAG= ‘N’ then 

    select Min(client_h.DT) from client_h where client_h.FLAG=‘Y’ 
    UPDATE client SET 
    client.FLAG_new  = client_h.FLAG, 
    client.DT_new = client_h.D


    Else 
    select Min(client_h.DT) from client_h where client_h.FLAG=‘L’ 

    UPDATE client SET 
    client.FLAG_new  = client_h.FLAG, 
    client.DT_new = client_h.DT

Answer 1

以下查询在PostgreSQL中产生所需的结果。

表“客户”

    | col_name | type      |
    | -------- | --------- |
    | id       | integer   |
    | flag     | text      |
    | dt       | timestamp |
    | flag_new | text      |
    | dt_new   | timestamp |

表“ client_h”

   | col_name  | type      |
   | --------- | --------- |
   | client_id | integer   |
   | flag      | text      |
   | dt        | timestamp |

查询

 with new_client(id,flag,dt) as (
  select
   id,
   coalesce(ch.flag,c.flag),
   coalesce(ch.dt,c.dt)
  from client c
  left join lateral (
   select
    flag,dt
   from client_h
   where client_id=c.id and flag!='N'
   order by flag='Y' desc, flag='L' desc, dt
   limit 1
  ) ch on c.flag='N'
 )
 update client set flag_new = nc.flag , dt_new = nc.dt
 from new_client nc
 where nc.id=client.id

Answer 2

对于mysql-不在集合中使用case语句。

DROP TABLE IF EXISTS CLIENT,CLIENT_H;
CREATE TABLE CLIENT (ID INT, FLAG_new VARCHAR(1), FLAG VARCHAR(1),  DT_new  DATE, DT  DATE);
CREATE TABLE CLIENT_H (ID INT, FLAG_new VARCHAR(1), FLAG VARCHAR(1),  DT_new  DATE, DT  DATE); 

TRUNCATE TABLE CLIENT;
INSERT INTO CLIENT VALUES 
(1,NULL,'Y',NULL,'2018-01-01'),
(2,NULL,'L',NULL,'2018-01-01'),
(3,NULL,'N',NULL,'2018-01-01'),
(4,NULL,'K',NULL,'2018-01-01');

INSERT INTO CLIENT_H VALUES 
(1,NULL,'Y',NULL,'2018-01-01'),
(2,NULL,'L',NULL,'2018-01-01'),
(3,NULL,'K',NULL,'2018-01-01'),
(3,NULL,'Y',NULL,'2018-02-01'),
(4,NULL,'M',NULL,'2018-01-01'),
(4,NULL,'L',NULL,'2018-03-01'),
(4,NULL,'K',NULL,'2018-04-01');

UPDATE CLIENT C
LEFT JOIN (SELECT * FROM CLIENT_H H WHERE DT = (SELECT MIN(DT) FROM CLIENT_H H1 WHERE H1.ID = H.ID AND H1.FLAG = 'Y')) HY ON HY.ID = C.ID
LEFT JOIN (SELECT * FROM CLIENT_H H WHERE DT = (SELECT MIN(DT) FROM CLIENT_H H1 WHERE H1.ID = H.ID AND H1.FLAG = 'L')) HN ON HN.ID = C.ID
SET 
C.FLAG_NEW = CASE WHEN C.FLAG IN ('Y','L') THEN C.FLAG 
                      WHEN C.FLAG = 'N' AND HY.FLAG = 'Y' THEN HY.FLAG
                        WHEN HN.FLAG = 'L' THEN HN.FLAG
                 END,
C.DT_NEW =   CASE WHEN C.FLAG IN ('Y','L') THEN C.DT 
                      WHEN C.FLAG = 'N' AND HY.FLAG = 'Y' THEN HY.DT
                        WHEN HN.FLAG = 'L' THEN HN.DT
                 END
;

SELECT * FROM CLIENT; 

+------+----------+------+------------+------------+
| ID   | FLAG_new | FLAG | DT_new     | DT         |
+------+----------+------+------------+------------+
|    1 | Y        | Y    | 2018-01-01 | 2018-01-01 |
|    2 | L        | L    | 2018-01-01 | 2018-01-01 |
|    3 | Y        | N    | 2018-02-01 | 2018-01-01 |
|    4 | L        | K    | 2018-03-01 | 2018-01-01 |
+------+----------+------+------------+------------+
4 rows in set (0.00 sec)

sql服务器

UPDATE C
SET 
C.FLAG_NEW = CASE WHEN C.FLAG IN ('Y','L') THEN C.FLAG 
                      WHEN C.FLAG = 'N' AND HY.FLAG = 'Y' THEN HY.FLAG
                        WHEN HN.FLAG = 'L' THEN HN.FLAG
                 END,
C.DT_NEW =   CASE WHEN C.FLAG IN ('Y','L') THEN C.DT 
                      WHEN C.FLAG = 'N' AND HY.FLAG = 'Y' THEN HY.DT
                        WHEN HN.FLAG = 'L' THEN HN.DT
                 END
from client c
LEFT JOIN (SELECT * FROM CLIENT_H H WHERE DT = (SELECT MIN(DT) FROM CLIENT_H H1 WHERE H1.ID = H.ID AND H1.FLAG = 'Y')) HY ON HY.ID = C.ID
LEFT JOIN (SELECT * FROM CLIENT_H H WHERE DT = (SELECT MIN(DT) FROM CLIENT_H H1 WHERE H1.ID = H.ID AND H1.FLAG = 'L')) HN ON HN.ID = C.ID

如何使用条件搜索历史表并在同一表中更新？

2 个答案: