用Clr实现的sql表值函数splitIDs

 在我们需要批量删除数据，或者批量修改实体的状态时，为了性能我们会直接写一个存储过程，并将这一批数据的id用“,”分隔传递给一个存储过程，然后在存储过程中拆分这个字符串，然后执行删除或者更新状态操作。以前每次执行这种操作时我都会在存储过程中拆分字符串。现在sql server支持用.net clr的程序集写函数，存储过程等等。 

现在我们就牛刀小试，做一个clr的sql表值函数。该函数的功能就是传入一个用逗号分隔的数字id字符，返回一个只有一列id的表。
第一步：我们需要新建一个类库项目，并添加一个类SplitIDs

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Server;
using System.Collections;
using System.Data.SqlTypes;

public class SplitIDs
{
    [SqlFunction(FillRowMethodName = "FillRow")]
    public static IEnumerable DoSplit(String strIDs)
    {
        return strIDs.Split(',');
    }

    public static void FillRow(Object obj, out SqlInt64 id)
    {
        long value = 0;
        long.TryParse((string)obj, out value);
        id = new SqlInt64(value);
    }
}

有2个注意的点
1.     命名空间声明要去掉，我在测试的过程中刚开始有命名空间的声明，总是注册不成功，后来去掉了存储过程的声明，才注册上
2.     方法必须是静态的并且要有SqlFunction特性，表值函数的返回值是IEnurable

第二步：注册程序集到sql server中

USE [DB_Name]
GO
if (object_id('SplitIDs') is not null)
drop function splitIds;
GO
IF  EXISTS (SELECT * FROM sys.assemblies asms WHERE asms.name = N'SqlServerUtility')
DROP ASSEMBLY [SqlServerUtility]
go
CREATE ASSEMBLY SqlServerUtility 
FROM 'D:\Program Files\Microsoft SQL Server\90\UserDefinedAssembly\SqlServerUtility.dll' 
WITH PERMISSION_SET = SAFE
GO
CREATE FUNCTION SplitIDs(@ids Nvarchar(max))
RETURNS TABLE (id bigint)
AS 
EXTERNAL NAME SqlServerUtility.SplitIDs.DoSplit
GO
EXEC sp_configure "clr enabled",1   
RECONFIGURE
GO

注册过程中需要注意的是上面注册sql中的最后一块，配置在数据库中启用clr enabled属性。否则即使注册上了函数也不能执行。
注册好了，我们来一个小例子，测试一下函数的执行情况：
select * from splitIDs('1,2,9,1000');
select * from splitIDs('333');
select * from splitIDs(NULL);
执行结果一切正常。
-------------t-sql实现分隔------------
当然这个函数还可以用t-sql直接实现，实现代码如下：

Use DB_Name
GO
if (object_id('splitIds') is not null)
drop function splitIds;
GO
CREATE FUNCTION splitIds(
    @strIds varchar(max) 
)
RETURNS @IDs table (id bigint)
AS
BEGIN 
    declare @i int,@j int,@l int,@v bigint;
    SET @i = 0;
    SET @j = 0;
    SET @l = len(@strIds);
    while (@j < @l)
    BEGIN
        SET @j = charindex(',',@strIds,@i+1);
        IF @j = 0 set @j = @l+1;
        SET @v = cast(substring(@strIds,@i+1,@j-@i-1) as bigint);
        INSERT INTO @IDs(id)VALUES(@v)
        SET @i = @j;
    END
    RETURN ;
END
GO

最后测试一下用clr实现和sql直接实现的性能差别；我们声明一个很长的字符串变量，然后让clr的splitIDs和t-sql的splitIDs分别做拆分10次，比较他们的耗时

测试脚本 （在测试脚本中使用的函数名字分别是splitIDs_tsql,splitIDs_clr）

t-sql和clr实现的性能比较
declare @str varchar(8000);
set @str = '1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600,601,602,603,604,605,606,607,608,609,610,611,612,613,614,615,616,617,618,619,620,621,622,623,624,625,626,627,628,629,630,631,632,633,634,635,636,637,638,639,640,641,642,643,644,645,646,647,648,649,650,651,652,653,654,655,656,657,658,659,660,661,662,663,664,665,666,667,668,669,670,671,672,673,674,675,676,677,678,679,680,681,682,683,684,685,686,687,688,689,690,691,692,693,694,695,696,697,698,699,700,701,702,703,704,705,706,707,708,709,710,711,712,713,714,715,716,717,718,719,720,721,722,723,724,725,726,727,728,729,730,731,732,733,734,735,736,737,738,739,740,741,742,743,744,745,746,747,748,749,750,751,752,753,754,755,756,757,758,759,760,761,762,763,764,765,766,767,768,769,770,771,772,773,774,775,776,777,778,779,780,781,782,783,784,785,786,787,788,789,790,791,792,793,794,795,796,797,798,799,800,801,802,803,804,805,806,807,808,809,810,811,812,813,814,815,816,817,818,819,820,821,822,823,824,825,826,827,828,829,830,831,832,833,834,835,836,837,838,839,840,841,842,843,844,845,846,847,848,849,850,851,852,853,854,855,856,857,858,859,860,861,862,863,864,865,866,867,868,869,870,871,872,873,874,875,876,877,878,879,880,881,882,883,884,885,886,887,888,889,890,891,892,893,894,895,896,897,898,899,900,901,902,903,904,905,906,907,908,909,910,911,912,913,914,915,916,917,918,919,920,921,922,923,924,925,926,927,928,929,930,931,932,933,934,935,936,937,938,939,940,941,942,943,944,945,946,947,948,949,950,951,952,953,954,955,956,957,958,959,960,961,962,963,964,965,966,967,968,969,970,971,972,973,974,975,976,977,978,979,980,981,982,983,984,985,986,987,988,989,990,991,992,993,994,995,996,997,998,999';
declare @t datetime,@cn int;
set nocount on;
set @cn = 10;
set @t = getdate();
while @cn > 0
begin
    select * from splitIDs_tsql(@str)
    set @cn = @cn -1;
end
print 'splitIDs_tsql执行时间' + cast(datediff(millisecond,@t,getdate()) as varchar(100))
set @cn = 10;
set @t = getdate();
while @cn > 0
begin
    select * from splitIDs_clr(@str)
    set @cn = @cn -1;
end
print 'splitIDs_clr执行时间' + cast(datediff(millisecond,@t,getdate()) as varchar(100))
set nocount off

执行的结果是：
splitIDs_tsql执行时间10060
splitIDs_clr执行时间266

很明显，用clr写的拆分函数要比tsql的拆分函数快大约50倍。

全文结束