数据库中各种字符串的截取函数

　　今天看见有人再问数据库中的数据截取了，我就和大家分享一下我看过的一篇有关这方面的文章吧。

　　

--各种字符串截取函数
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[f_splitSTR]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_splitSTR]
GO
 
--1 循环截取法
CREATE FUNCTION f_splitSTR(
@s   varchar(8000),   --待分拆的字符串
@split varchar(10)     --数据分隔符
)RETURNS @re TABLE(col varchar(100))
AS
BEGIN
    DECLARE @splitlen int
    SET @splitlen=LEN(@split+'a')-2
    WHILE CHARINDEX(@split,@s)>0
    BEGIN
        INSERT @re VALUES(LEFT(@s,CHARINDEX(@split,@s)-1))
        SET @s=STUFF(@s,1,CHARINDEX(@split,@s)+@splitlen,'')
    END
    INSERT @re VALUES(@s)
    RETURN
END
GO
 
 
/*==============================================*/
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[f_splitSTR]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_splitSTR]
GO
 
--2 使用临时性分拆辅助表法
CREATE FUNCTION f_splitSTR(
@s   varchar(8000),  --待分拆的字符串
@split varchar(10)     --数据分隔符
)RETURNS @re TABLE(col varchar(100))
AS
BEGIN
    --创建分拆处理的辅助表(用户定义函数中只能操作表变量)
    DECLARE @t TABLE(ID int IDENTITY,b bit)
    INSERT @t(b) SELECT TOP 8000 0 FROM syscolumns a,syscolumns b
 
    INSERT @re SELECT SUBSTRING(@s,ID,CHARINDEX(@split,@s+@split,ID)-ID)
    FROM @t
    WHERE ID<=LEN(@s+'a') 
        AND CHARINDEX(@split,@split+@s,ID)=ID
    RETURN
END
GO
 
/*==============================================*/
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[f_splitSTR]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_splitSTR]
GO
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[tb_splitSTR]') and objectproperty(id,N'IsUserTable')=1)
drop table [dbo].[tb_splitSTR]
GO
 
--2.1 使用永久性分拆辅助表法
--字符串分拆辅助表
SELECT TOP 8000 ID=IDENTITY(int,1,1) INTO dbo.tb_splitSTR
FROM syscolumns a,syscolumns b
GO
 
--字符串分拆处理函数
CREATE FUNCTION f_splitSTR(
@s     varchar(8000),  --待分拆的字符串
@split  varchar(10)     --数据分隔符
)RETURNS TABLE
AS
RETURN(
    SELECT col=CAST(SUBSTRING(@s,ID,CHARINDEX(@split,@s+@split,ID)-ID) as varchar(100))
    FROM tb_splitSTR
    WHERE ID<=LEN(@s+'a') 
        AND CHARINDEX(@split,@split+@s,ID)=ID)
GO
 
 
/*==============================================*/
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[f_splitSTR]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_splitSTR]
GO
 
--3 将数据项按数字与非数字再次拆份
CREATE FUNCTION f_splitSTR(
@s   varchar(8000),    --待分拆的字符串
@split varchar(10)     --数据分隔符
)RETURNS @re TABLE(No varchar(100),Value varchar(20))
AS
BEGIN
    --创建分拆处理的辅助表(用户定义函数中只能操作表变量)
    DECLARE @t TABLE(ID int IDENTITY,b bit)
    INSERT @t(b) SELECT TOP 8000 0 FROM syscolumns a,syscolumns b
 
    INSERT @re 
    SELECT    No=REVERSE(STUFF(col,1,PATINDEX('%[^-^.^0-9]%',col+'a')-1,'')),
        Value=REVERSE(LEFT(col,PATINDEX('%[^-^.^0-9]%',col+'a')-1))
    FROM(
        SELECT col=REVERSE(SUBSTRING(@s,ID,CHARINDEX(@split,@s+@split,ID)-ID))
        FROM @t
        WHERE ID<=LEN(@s+'a') 
            AND CHARINDEX(@split,@split+@s,ID)=ID)a
    RETURN
END
GO
 
 
/*==============================================*/
 
if exists (select * from dbo.ss where id = object_id(N'[dbo].[f_splitSTR]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_splitSTR]
GO
 
--3.1 分拆短信数据
CREATE FUNCTION f_splitSTR(@s varchar(8000))
RETURNS @re TABLE(split varchar(10),value varchar(100))
AS
BEGIN
    DECLARE @splits TABLE(split varchar(10),splitlen as LEN(split))
    INSERT @splits(split)
    SELECT 'AC' UNION ALL
    SELECT 'BC' UNION ALL
    SELECT 'CC' UNION ALL
    SELECT 'DC'   
    DECLARE @pos1 int,@pos2 int,@split varchar(10),@splitlen int
    SELECT TOP 1 
        @pos1=1,@split=split,@splitlen=splitlen
    FROM @splits
    WHERE @s LIKE split+'%'
    WHILE @pos1>0
    BEGIN
        SELECT TOP 1
            @pos2=CHARINDEX(split,@s,@splitlen+1)
        FROM @splits
        WHERE CHARINDEX(split,@s,@splitlen+1)>0
        ORDER BY CHARINDEX(split,@s,@splitlen+1)
        IF @@ROWCOUNT=0
        BEGIN
            INSERT @re VALUES(@split,STUFF(@s,1,@splitlen,''))
            RETURN
        END
        ELSE
        BEGIN
            INSERT @re VALUES(@split,SUBSTRING(@s,@splitlen+1,@pos2-@splitlen-1))
            SELECT TOP 1 
                @pos1=1,@split=split,@splitlen=splitlen,@s=STUFF(@s,1,@pos2-1,'')
            FROM @splits
            WHERE STUFF(@s,1,@pos2-1,'') LIKE split+'%'
        END
    END
    RETURN
END
GO

 　　在增加知识的同时，也希望能帮助有需要的盆友，同时也希望大家共同进步，互相学习。