数字辅助表是一个连续整数的数列，通常用来实现多种不同的查询任务。大多分两类：足够大物理数字表和表函数，前者可以称为静态的，后者可以称为动态且按需生产。
物理数字表 物理数字表通常存在一个物理表，表记录相对足够大，相关的T-
SQL代码如下：
1 IF OBJECT_ID(N'dbo.Nums', 'U') IS NOT NULL 2 BEGIN 3 DROP TABLE dbo.Nums; 4 END 5 GO 6 7 CREATE TABLE dbo.Nums 8 ( 9 Num INT NOT NULL,10 CONSTRAINT PK_U_CL_Nums_Num PRIMARY KEY CLUSTERED11 (12 Num ASC13 ) 14 );15 GO16 17 INSERT INTO dbo.Nums (Num)18 SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum19 FROM master.dbo.spt_values;20 GO
注意：如何填充物理数字表的方法很多，为了演示作用使用了一种。
测试的T-SQL代码如下：
1 SELECT Num2 FROM dbo.Nums;3 GO
执行后的查询结果如下：
表函数 表函数实现使用交叉连接和CTE，
Server.aspx' >SQL Server 2005和以上版本的T-SQL代码如下：
1 IF OBJECT_ID(N'dbo.ufn_GetNums', N'IF') IS NOT NULL 2 BEGIN 3 DROP TABLE dbo.ufn_GetNums; 4 END 5 GO 6 7 --================================== 8 -- 功能: 获取指定范围的数字数列 9 -- 说明: 交叉最后层级的CTE得到的数据行：在L级（从0开始计数）得到的行的总数为2^2^L。10 -- 例如：在5级就会得到4 294 967 596行。5级的CTE提供了超过40亿的行。11 -- 作者: XXX12 -- 创建: yyyy-MM-dd13 -- 修改: yyyy-MM-dd XXX 修改内容描述14 --==================================15 CREATE FUNCTION dbo.ufn_GetNums16 (17 @bintLow BIGINT,18 @bintHigh BIGINT19 ) RETURNS TABLE20 AS21 RETURN 22 WITH23 L0 AS (SELECT c FROM (VALUES(1), (1)) AS LO(c)),24 L1 AS (SELECT 1 AS c FROM L0 AS T CROSS JOIN L0 AS T2),25 L2 AS (SELECT 1 AS c FROM L1 AS T CROSS JOIN L1 AS T2),26 L3 AS (SELECT 1 AS c FROM L2 AS T CROSS JOIN L2 AS T2),27 L4 AS (SELECT 1 AS c FROM L3 AS T CROSS JOIN L3 AS T2),28 L5 AS (SELECT 1 AS c FROM L4 AS T CROSS JOIN L4 AS T2),29 Nums AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum FROM L5)30 31 SELECT TOP (@bintHigh - @bintLow + 1) @bintLow + RowNum - 1 AS Num32 FROM Nums33 ORDER BY RowNum ASC;34 GO
SQL Server 2012增加了有关分页的新特性，相关的T-SQL代码如下:
1 IF OBJECT_ID(N'dbo.ufn_GetNums2', N'IF') IS NOT NULL 2 BEGIN 3 DROP TABLE dbo.ufn_GetNums2; 4 END 5 GO 6 7 --================================== 8 -- 功能: 获取指定范围的数字数列 9 -- 说明: 交叉最后层级的CTE得到的数据行：在L级（从0开始计数）得到的行的总数为2^2^L。10 -- 例如：在5级就会得到4 294 967 596行。5级的CTE提供了超过40亿的行。 11 -- 作者: XXX12 -- 创建: yyyy-MM-dd13 -- 修改: yyyy-MM-dd XXX 修改内容描述14 --==================================15 CREATE FUNCTION dbo.ufn_GetNums216 (17 @bintLow BIGINT,18 @bintHigh BIGINT19 ) RETURNS TABLE20 AS21 RETURN 22 WITH23 L0 AS (SELECT c FROM (VALUES(1), (1)) AS LO(c)),24 L1 AS (SELECT 1 AS c FROM L0 AS T CROSS JOIN L0 AS T2),25 L2 AS (SELECT 1 AS c FROM L1 AS T CROSS JOIN L1 AS T2),26 L3 AS (SELECT 1 AS c FROM L2 AS T CROSS JOIN L2 AS T2),27 L4 AS (SELECT 1 AS c FROM L3 AS T CROSS JOIN L3 AS T2),28 L5 AS (SELECT 1 AS c FROM L4 AS T CROSS JOIN L4 AS T2),29 Nums AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum FROM L5)30 31 SELECT @bintLow + RowNum - 1 AS Num32 FROM Nums33 ORDER BY RowNum ASC34 OFFSET 0 ROWS FETCH FIRST @bintHigh - @bintLow + 1 ROWS ONLY;35 GO36
以函数ufn_GetNums为例，演示相关的效果。获取指定范围的数字序列的T-SQL代码如下：
SELECT NumFROM dbo.ufn_GetNums(11, 20);GO
执行后的查询结果如下：
博友如有其他更好的解决方案，也请不吝赐教，万分感谢。 参考清单列表1、《Microsoft SQL Server 2012 High-Performance T-SQL Using Window Functions》 作者 Itzik Ben-Gan（美国）（SQL Server Inside 有关书籍的作者）原标题：SQL Server数字辅助表的实现
关键词：sql
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