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SQL Server 實(shí)現(xiàn)數(shù)字輔助表實(shí)例代碼

 更新時(shí)間：2016年10月19日 11:55:45   投稿：lqh  
這篇文章主要介紹了SQL Server 實(shí)現(xiàn)數(shù)字輔助表的相關(guān)資料,并附實(shí)例代碼，需要的朋友可以參考下

數(shù)字輔助表是一個(gè)連續(xù)整數(shù)的數(shù)列，通常用來(lái)實(shí)現(xiàn)多種不同的查詢(xún)?nèi)蝿?wù)。大多分兩類(lèi)：足夠大物理數(shù)字表和表函數(shù)，前者可以稱(chēng)為靜態(tài)的，后者可以稱(chēng)為動(dòng)態(tài)且按需生產(chǎn)。

物理數(shù)字表

    物理數(shù)字表通常存在一個(gè)物理表，表記錄相對(duì)足夠大，相關(guān)的T-SQL代碼如下：

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：如何填充物理數(shù)字表的方法很多，為了演示作用使用了一種。

測(cè)試的T-SQL代碼如下：

1 SELECT Num
2 FROM dbo.Nums;
3 GO

執(zhí)行后的查詢(xún)結(jié)果如下：

 表函數(shù)

    表函數(shù)實(shí)現(xiàn)使用交叉連接和CTE，SQL Server 2005和以上版本的T-SQL代碼如下：

IF OBJECT_ID(N'dbo.ufn_GetNums', N'IF') IS NOT NULL
BEGIN
  DROP TABLE dbo.ufn_GetNums;
END
GO
 
--==================================
-- 功能: 獲取指定范圍的數(shù)字?jǐn)?shù)列
-- 說(shuō)明: 交叉最后層級(jí)的CTE得到的數(shù)據(jù)行：在L級(jí)（從0開(kāi)始計(jì)數(shù)）得到的行的總數(shù)為2^2^L。
--    例如：在5級(jí)就會(huì)得到4 294 967 596行。5級(jí)的CTE提供了超過(guò)40億的行。
-- 作者: XXX
-- 創(chuàng)建: yyyy-MM-dd
-- 修改: yyyy-MM-dd XXX 修改內(nèi)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增加了有關(guān)分頁(yè)的新特性，相關(guān)的T-SQL代碼如下:

IF OBJECT_ID(N'dbo.ufn_GetNums2', N'IF') IS NOT NULL
BEGIN
  DROP TABLE dbo.ufn_GetNums2;
END
GO
 
--==================================
-- 功能: 獲取指定范圍的數(shù)字?jǐn)?shù)列
-- 說(shuō)明: 交叉最后層級(jí)的CTE得到的數(shù)據(jù)行：在L級(jí)（從0開(kāi)始計(jì)數(shù)）得到的行的總數(shù)為2^2^L。
--    例如：在5級(jí)就會(huì)得到4 294 967 596行。5級(jí)的CTE提供了超過(guò)40億的行。 
-- 作者: XXX
-- 創(chuàng)建: yyyy-MM-dd
-- 修改: yyyy-MM-dd XXX 修改內(nèi)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

以函數(shù)ufn_GetNums為例，演示相關(guān)的效果。獲取指定范圍的數(shù)字序列的T-SQL代碼如下：

SELECT Num
FROM dbo.ufn_GetNums(11, 20);
GO

執(zhí)行后的查詢(xún)結(jié)果如下：


 

博友如有其他更好的解決方案，也請(qǐng)不吝賜教，萬(wàn)分感謝。

參考清單列表

1、《Microsoft SQL Server 2012 High-Performance T-SQL Using Window Functions》 作者 Itzik Ben-Gan（美國(guó)）（SQL Server Inside 有關(guān)書(shū)籍的作者）

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