sql server 累计求和方法

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

看了一眼自关联，没搞懂，试了一下也没成功。

over方式一下结果就出来了，好用。

 

/* 需求：累计求和六种算法效率比较 作者：felix 日期：2020-06-23  */ --第一步，准备测试数据 --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，创建记录时间的表格 --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,--开始时间 -- et DATETIME2,--结束时间 -- idiff AS DATEDIFF(ms, bt, et)--所用的毫秒数 --); --第一种方法，自连接法，sql server 2008以上版本测试通过，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 ('自连接', @bt, @et); --ORDER BY a.i; GO ; --第二种方法，递归，sql server 2008以上版本测试通过，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 ('递归', @bt, @et); GO --第三种方法，over 子句，sql server 2012测试通过，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 --第四种，相关子查询，sql server 2008以上版本测试通过，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 --内部查询 FROM dbo.t AS outquery; DECLARE @et DATETIME2 = GETDATE(); INSERT INTO dbo.record_time ( 算法, bt, et ) VALUES ('相关子查询', @bt, @et); --ORDER BY outquery.i; --外部查询 GO --游标方法，有两种方法可以实现，一种是临时表更新，一种是变量叠加更新，157255661.40 --先增加一个存储累计和的列 --第5种，游标_临时表更新 --ALTER TABLE dbo.t ADD total_d MONEY DEFAULT (0);--只运行一次 GO DECLARE @bt DATETIME2 = GETDATE(); DECLARE @t TABLE --定义表变量，存储累计求和临时结果 ( 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 ('游标_临时表更新', @bt, @et); GO --第6种，游标_变量叠加更新 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 ('游标_变量叠加更新', @bt, @et); --执行时间 over子句<游标临时表更新<游标变量叠加更新<自连接<相关子查询<递归查询