这篇文章主要介绍SQL Server中怎么样实现数字辅助表的内容，一些朋友可能不是很了解数字辅助表，其实数字辅助表有很大的用处，接下来我们一起来了解看看SQL Server 实现数字辅助表的方法。
 
    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：
1 SELECT Num
2 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，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2^2^L。
—    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。
— 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(1), (1)) AS LO(c)),
    L1 AS (SELECT 1 AS c FROM L0 AS T CROSS JOIN L0 AS T2),
    L2 AS (SELECT 1 AS c FROM L1 AS T CROSS JOIN L1 AS T2),
    L3 AS (SELECT 1 AS c FROM L2 AS T CROSS JOIN L2 AS T2),
    L4 AS (SELECT 1 AS c FROM L3 AS T CROSS JOIN L3 AS T2),
    L5 AS (SELECT 1 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 + 1) @bintLow + RowNum – 1 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2^2^L。
—    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。
— 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(1), (1)) AS LO(c)),
    L1 AS (SELECT 1 AS c FROM L0 AS T CROSS JOIN L0 AS T2),
    L2 AS (SELECT 1 AS c FROM L1 AS T CROSS JOIN L1 AS T2),
    L3 AS (SELECT 1 AS c FROM L2 AS T CROSS JOIN L2 AS T2),
    L4 AS (SELECT 1 AS c FROM L3 AS T CROSS JOIN L3 AS T2),
    L5 AS (SELECT 1 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 – 1 AS Num
  FROM Nums
  ORDER BY RowNum ASC
  OFFSET 0 ROWS FETCH FIRST @bintHigh – @bintLow + 1 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(11, 20);
GO