SQL Server数字辅助表的实现

    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：

 IF OBJECT_ID(N'dbo.Nums', 'U') IS NOT NULL
 BEGIN
     DROP TABLE dbo.Nums;
 END
 GO

 CREATE TABLE dbo.Nums
 (
     Num INT NOT NULL,
     CONSTRAINT PK_U_CL_Nums_Num PRIMARY KEY CLUSTERED
     (
         Num ASC
     )
 );
 GO

 INSERT INTO dbo.Nums (Num)
 SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum
 FROM master.dbo.spt_values;
 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：

 SELECT Num
 FROM dbo.Nums;
 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，SQL Server 2005和以上版本的T-SQL代码如下：

 IF OBJECT_ID(N'dbo.ufn_GetNums', N'IF') IS NOT NULL
 BEGIN
     DROP TABLE dbo.ufn_GetNums;
 END
 GO

 --==================================
 -- 功能: 获取指定范围的数字数列
 -- 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^^L。
 --       例如：在5级就会得到4   596行。5级的CTE提供了超过40亿的行。
 -- 作者: XXX
 -- 创建: yyyy-MM-dd
 -- 修改: yyyy-MM-dd XXX 修改内容描述
 --==================================
 CREATE FUNCTION dbo.ufn_GetNums
 (
     @bintLow BIGINT,
     @bintHigh BIGINT
 ) RETURNS TABLE
 AS
 RETURN
     WITH
         L0 AS (SELECT c FROM (VALUES(), ()) AS LO(c)),
         L1 AS (SELECT  AS c FROM L0 AS T CROSS JOIN L0 AS T2),
         L2 AS (SELECT  AS c FROM L1 AS T CROSS JOIN L1 AS T2),
         L3 AS (SELECT  AS c FROM L2 AS T CROSS JOIN L2 AS T2),
         L4 AS (SELECT  AS c FROM L3 AS T CROSS JOIN L3 AS T2),
         L5 AS (SELECT  AS c FROM L4 AS T CROSS JOIN L4 AS T2),
         Nums AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum FROM L5)

     SELECT TOP (@bintHigh - @bintLow + ) @bintLow + RowNum -  AS Num
     FROM Nums
     ORDER BY RowNum ASC;
 GO

SQL Server 2012增加了有关分页的新特性，相关的T-SQL代码如下:

 IF OBJECT_ID(N'dbo.ufn_GetNums2', N'IF') IS NOT NULL
 BEGIN
     DROP TABLE dbo.ufn_GetNums2;
 END
 GO

 --==================================
 -- 功能: 获取指定范围的数字数列
 -- 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^^L。
 --       例如：在5级就会得到4   596行。5级的CTE提供了超过40亿的行。
 -- 作者: XXX
 -- 创建: yyyy-MM-dd
 -- 修改: yyyy-MM-dd XXX 修改内容描述
 --==================================
 CREATE FUNCTION dbo.ufn_GetNums2
 (
     @bintLow BIGINT,
     @bintHigh BIGINT
 ) RETURNS TABLE
 AS
 RETURN
     WITH
         L0 AS (SELECT c FROM (VALUES(), ()) AS LO(c)),
         L1 AS (SELECT  AS c FROM L0 AS T CROSS JOIN L0 AS T2),
         L2 AS (SELECT  AS c FROM L1 AS T CROSS JOIN L1 AS T2),
         L3 AS (SELECT  AS c FROM L2 AS T CROSS JOIN L2 AS T2),
         L4 AS (SELECT  AS c FROM L3 AS T CROSS JOIN L3 AS T2),
         L5 AS (SELECT  AS c FROM L4 AS T CROSS JOIN L4 AS T2),
         Nums AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS RowNum FROM L5)

     SELECT @bintLow + RowNum -  AS Num
     FROM Nums
     ORDER BY RowNum ASC
     OFFSET  ROWS FETCH FIRST @bintHigh - @bintLow +  ROWS ONLY;
 GO
  

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 Num
FROM dbo.ufn_GetNums(, );
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）