技術標籤：SQL server 筆記sql資料庫

題目

有如下一張表Dscore

--測試資料
ways-1
CREATE TABLE Dscore(
monthtime int,
score int
);
INSERT INTO Dscore VALUES (1,10);
INSERT INTO Dscore VALUES (2,20);
INSERT INTO Dscore VALUES (3,30);
INSERT INTO Dscore VALUES (4,50);
INSERT INTO Dscore VALUES (5,40);
INSERT INTO Dscore VALUES (
 
6,20);
INSERT INTO Dscore VALUES (7,30);

SELECT * FROM Dscore

--ways-2 建立自增加的monthtime或id列
CREATE TABLE Dscore(
monthtime int Identity(1,1),
score int
);
INSERT INTO Dscore(score) VALUES (10);
INSERT INTO Dscore(score) VALUES (20);
INSERT INTO Dscore(score) VALUES (30);
INSERT INTO Dscore(score) VALUES
 
 (50);
INSERT INTO Dscore(score) VALUES (40);
INSERT INTO Dscore(score) VALUES (20);
INSERT INTO Dscore(score) VALUES (30);

SELECT * FROM Dscore

希望將每個月之前的月份進行累加，例如2月份的score=10+20，3月份的score=10+20+30，4月份的score=10+20+30+50，以此類推。

--ways-子查詢
select monthtime,(select sum(score) from  
Dscore B where B.monthtime <=
 
 A.monthtime )score from Dscore A 

--ways-連線查詢
select a.monthtime,sum(b.score)score from 
Dscore a,Dscore b where b.monthtime <= a.monthtime group by a.monthtime

思路：當日期這一列如果為數值型等可比較大小的型別時，可使用上述方法；當日期這一列為文字型等不可比較大小的型別時，如下面這張表

--測試資料
CREATE TABLE DDscore(
monthtime varchar(23),
total int
);
INSERT INTO DDscore VALUES ('一月份',10);
INSERT INTO DDscore VALUES ('二月份',20);
INSERT INTO DDscore VALUES ('三月份',30);
INSERT INTO DDscore VALUES ('四月份',50);
INSERT INTO DDscore VALUES ('五月份',40);
INSERT INTO DDscore VALUES ('六月份',20);
INSERT INTO DDscore VALUES ('七月份',30);

select * from DDscore

先建立臨時表，帶可比較大小的id列

--建立臨時表
SELECT IDENTITY(int,1,1) as id,* INTO #D FROM DDscore SELECT * FROM #D  

再使用之前的方法

select monthtime,(select sum(score) from  #D B where B.id <= A.id )score from #D A 

補充：刪除臨時表

--刪除臨時表
if object_id('tempdb..#D') is not null Begin  
    drop table #D
End