sql server 累計求和方法

原文：https://zhuanlan.zhihu.com/p/150291837

看了一眼自關聯，沒搞懂，試了一下也沒成功。

over方式一下結果就出來了，好用。

 

/* 需求：累計求和六種算法效率比較 作者：felix 日期：2020-06-23  */ --第一步，准備測試數據 --IF OBJECT_ID(N'dbo.t') IS NOT NULL -- DROP TABLE dbo.t; --GO --CREATE TABLE dbo.t --( -- i BIGINT IDENTITY(1, 1) PRIMARY KEY, -- d MONEY --); --INSERT t --( -- d --) --SELECT TOP 31465 -- ROUND(10000 * RAND(CHECKSUM(NEWID())), 2) --FROM sys.all_objects AS a -- CROSS JOIN sys.all_objects;  ----第二步，創建記錄時間的表格 --IF OBJECT_ID(N'dbo.record_time') IS NOT NULL -- DROP TABLE dbo.record_time; --GO --CREATE TABLE dbo.record_time --( -- i INT IDENTITY PRIMARY KEY, -- 算法 NVARCHAR(10), -- bt DATETIME2,--開始時間 -- et DATETIME2,--結束時間 -- idiff AS DATEDIFF(ms, bt, et)--所用的毫秒數 --); --第一種方法，自連接法，sql server 2008以上版本測試通過，157255661.40 SET STATISTICS TIME OFF; SET STATISTICS IO OFF; GO DECLARE @bt DATETIME2 = GETDATE(); SELECT a.i, a.d, SUM(b.d) AS total_sum FROM dbo.t AS a INNER JOIN dbo.t AS b ON b.i <= a.i GROUP BY a.i, a.d; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('自連接', @bt, @et); --ORDER BY a.i; GO ; --第二種方法，遞歸，sql server 2008以上版本測試通過，157255661.40 DECLARE @bt DATETIME2 = GETDATE(); WITH cte_total_sum AS (SELECT i, d, d AS total_sum FROM dbo.t WHERE i = 1 UNION ALL SELECT s.i, s.d, p.total_sum + s.d AS total_sum FROM dbo.t AS s INNER JOIN cte_total_sum AS p ON s.i - 1 = p.i) SELECT * FROM cte_total_sum OPTION (MAXRECURSION 0); DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('遞歸', @bt, @et); GO --第三種方法，over 子句，sql server 2012測試通過，sql server 2008不支持，157255661.40 DECLARE @bt DATETIME2 = GETDATE(); SELECT i, d, SUM(d) OVER (ORDER BY i) AS total_sum FROM dbo.t; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('over子句', @bt, @et); GO --第四種，相關子查詢，sql server 2008以上版本測試通過，156625045.22 DECLARE @bt DATETIME2 = GETDATE(); SELECT outquery.i, outquery.d, ( SELECT SUM(innerq.d) FROM dbo.t AS innerq WHERE innerq.i <= outquery.i ) AS ct --內部查詢 FROM dbo.t AS outquery; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('相關子查詢', @bt, @et); --ORDER BY outquery.i; --外部查詢 GO --游標方法，有兩種方法可以實現，一種是臨時表更新，一種是變量疊加更新，157255661.40 --先增加一個存儲累計和的列 --第5種，游標_臨時表更新 --ALTER TABLE dbo.t ADD total_d MONEY DEFAULT (0);--只運行一次 GO DECLARE @bt DATETIME2 = GETDATE(); DECLARE @t TABLE --定義表變量，存儲累計求和臨時結果 ( i INT PRIMARY KEY IDENTITY, d MONEY, total_d MONEY ); DECLARE @i INT = 0, @d MONEY = 0, @total_d MONEY = 0; DECLARE c1 CURSOR FOR SELECT i, d FROM dbo.t ORDER BY i; OPEN c1; FETCH c1 INTO @i, @d; WHILE @@FETCH_STATUS = 0 BEGIN SET @total_d += @d; INSERT INTO @t ( d, total_d ) VALUES (@d, @total_d); FETCH c1 INTO @i, @d; END; CLOSE c1; DEALLOCATE c1; UPDATE dbo.t SET total_d = b.total_d FROM dbo.t AS a INNER JOIN @t AS b ON a.i = b.i; SELECT * FROM dbo.t; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('游標_臨時表更新', @bt, @et); GO --第6種，游標_變量疊加更新 DECLARE @bt DATETIME2 = GETDATE(); DECLARE @i INT = 0, @d MONEY = 0, @total_d MONEY = 0; DECLARE c1 CURSOR FOR SELECT i, d FROM dbo.t; --ORDER BY i; OPEN c1; FETCH c1 INTO @i, @d; WHILE @@FETCH_STATUS = 0 BEGIN SET @total_d += @d; UPDATE dbo.t SET total_d = @total_d WHERE i = @i; FETCH c1 INTO @i, @d; END; CLOSE c1; DEALLOCATE c1; SELECT * FROM dbo.t; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('游標_變量疊加更新', @bt, @et); --執行時間 over子句<游標臨時表更新<游標變量疊加更新<自連接<相關子查詢<遞歸查詢