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/*
Microsoft SQL Server 2017 (RTM-CU5) (KB4092643) - 14.0.3023.8 (X64) Mar 2 2018 18:24:44
Copyright (C) 2017 Microsoft Corporation Enterprise Edition: Core-based Licensing (64-bit) on
Windows 10 Pro 10.0 <X64> (Build 15063: )
*/
--备用函数
if object_id('getnums') is not null drop function getnums
go
create function [dbo].[getnums]
(@n int)
returns table as
return
with t1 as(select 1 n union all select 1)
,t2 as(select 1 n from t1,t1 a,t1 b,t1 c)
,t3 as(select 1 n from t2,t2 a,t2 b,t2 c)
,t4 as(select 1 n from t3,t3 a)
select top(@n) row_number()over(order by(select 1)) n from t4 order by n
go
--1. 基于 xml path + row_number
if object_id('fn_split') is not null drop function fn_split
go
create function fn_split(@s nvarchar(max),@split nvarchar(2))
returns table
as
return
with
t0 as (select substring(@s,n,1)ch,n from getnums(len(@s)))
,
t1 as(select ch,rid=n-row_number()over(order by n)+1 from t0 where ch<>@split)
select
rid,
keys=(select ''+ch from t1 b where b.rid=a.rid for xml path(''))
from t1 a
group by rid
go
--2. 基于 xml 的nodes
IF OBJECT_ID('[dbo].[Fun_String2ToStringArray]') IS NOT NULL
DROP FUNCTION [dbo].[Fun_String2ToStringArray]
GO
CREATE FUNCTION [dbo].[Fun_String2ToStringArray](@str NVARCHAR(MAX), @split NVARCHAR(10))
RETURNS @table TABLE ([item] NVARCHAR(max))
AS
BEGIN
IF LEN(@split) = 0
BEGIN
SET @split = N','
END
DECLARE @xml XML;
SET @xml = CONVERT(XML, '<x><![CDATA[' + replace(CONVERT(VARCHAR(MAX), @str), @split, ']]></x><x><![CDATA[') + ']]></x>')
INSERT INTO @table
SELECT item
FROM (SELECT c.value('text()[1]', 'nvarchar(4000)') [item]
FROM @xml.nodes('/x') t(c)) t
WHERE item IS NOT NULL
RETURN
END
GO
--3. 从SQL Server2016起支持的分割表值函数 string_split , 不用写
--4. 下面是测试代码
DECLARE @str NVARCHAR(MAX);
SELECT @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';
SET NOCOUNT ON
SET STATISTICS IO ON
SET STATISTICS TIME ON
SELECT * FROM dbo.fn_split(@str,',') AS fs
SELECT * FROM dbo.[Fun_String2ToStringArray](@str,',') AS fs
SELECT * FROM string_split(@str,',') AS fs
/*
SQL Server 分析和编译时间:
CPU 时间 = 0 毫秒,占用时间 = 0 毫秒。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 0 毫秒。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 0 毫秒。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 0 毫秒。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 0 毫秒。
表 'Worktable'。扫描计数 0,逻辑读取 0 次,物理读取 0 次,预读 0 次,lob 逻辑读取 0 次,lob 物理读取 0 次,lob 预读 0 次。
SQL Server 执行时间:
CPU 时间 = 1187 毫秒,占用时间 = 1204 毫秒。
表 '#BD909E0C'。扫描计数 1,逻辑读取 2 次,物理读取 0 次,预读 0 次,lob 逻辑读取 0 次,lob 物理读取 0 次,lob 预读 0 次。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 181 毫秒。
SQL Server 执行时间:
CPU 时间 = 0 毫秒,占用时间 = 3 毫秒。
*/
专门在SQL Server2017 下测试了三种分割函数, 还是系统自带的 string_split 最快……
当然, 楼主的精神可嘉, 值得我们学习。--1. 创建fn_Split函数. ( 切分字符串, 返回一个列名为id的表 )
IF EXISTS(
SELECT *
FROM dbo.sysobjects
WHERE id = OBJECT_ID('fn_Split')
AND (TYPE = 'FN' OR TYPE = 'TF' OR TYPE = 'IF')
)
DROP FUNCTION fn_Split
GO
CREATE FUNCTION [dbo].[fn_Split]
(
@str VARCHAR(MAX),
@separator VARCHAR(10)
)
RETURNS TABLE
AS
RETURN
(
--Example: SELECT id FROM fn_Split('a,b,d,c',',')
SELECT B.id
FROM (
(
--A 的作用只是生成 '<v>a</v><v>b</v><v>d</v><v>c</v>' 的XML格式的数据, 提供数据源
SELECT [value] = CONVERT(XML, '<v>' + REPLACE(@str, @separator, '</v><v>') + '</v>')
) A
OUTER APPLY
(
--B 的作用是将A中的 XML 数据的值枚举出来转换成行
SELECT id = N.v.value('.', 'varchar(100)') FROM A.[value].nodes('/v') N(v)
) B
)
)
GO