根据日期和条件合并 table

Question

我关注table：

DROP TABLE IF EXISTS t

CREATE TABLE t
(
    id INT IDENTITY PRIMARY KEY,
    dt datetime,
    type int,
    grp int,
    typecol1 varchar(10),
    typecol2 varchar(10),
    typecol3 varchar(10),
    typecol4 varchar(10)
)

INSERT INTO t (dt,type,grp,typecol1,typecol2,typecol3,typecol4) 
VALUES
('2019-01-15',1,1,'A',null,null,null),
('2019-01-15',2,2,null,'B',null,null),
('2019-01-15',3,3,null,null,'C',null),
('2019-01-15',4,4,null,null,null,'D'),
('2019-02-15',1,1,'AA',null,null,null),
('2019-02-15',4,2,null,null,null,'DD'),
('2019-03-15',3,1,null,null,'CCC',null),
('2019-04-15',2,1,null,'BBBB',null,NULL);

在这个 table type 中将是 1,2,3,4.. 这里 date 和 type 都是复合键。

如果存在相同日期，我需要将行合并到单行并仅根据以下条件合并

if same date & 
   type=1 then merge to typecol1
   type=2 then merge to typecol2
   type=3 then merge to typecol3
   type=4 then merge to typecol4

grp col 基于运行日期计数。

Answer 1

尝试GROUP BY

FIDDLE DEMO

SELECT dt, MAX(typecol1) typecol1, MAX(typecol2) typecol2, MAX(typecol3) typecol3,
       MAX(typecol4) typecol4
FROM t
GROUP BY dt

输出

dt                  typecol1    typecol2    typecol3    typecol4
15/01/2019 00:00:00 A           B           C           D
15/02/2019 00:00:00 AA                                  DD
15/03/2019 00:00:00                         CCC 
15/04/2019 00:00:00             BBBB

Answer 2

您只需要按 ID 分组，对其余列进行 MAX() 聚合：

SELECT dt,MAX(typecol1) as typecol1,
          MAX(typecol2) as typecol2,
          MAX(typecol3) as typecol3,
          MAX(typecol4) as typecol4
  FROM t
 GROUP BY dt

Demo

根据日期和条件合并 table

Merge the table based on date and condition

sql

sql-server

sql-server-2017