sqlserver 循环截取字段中的某些字符

--循环按固定长度截取

--CJ2249301801,CJ2249300803,CJ2249301901,CJ2249302003 截取 形式301,300,301,302

CREATE FUNCTION [dbo].[FN_LOOPSUBSTRING](
@string NVARCHAR(MAX),
@spchar CHAR(1),
@strlen INT,
@eachstrEnoughLenStartIndex INT,
@eachstrEnoughLenEndIndex INT,
@eachstrNotEnoughLenStartIndex INT,
@eachstrNotEnoughLenEndIndex INT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN

 --DECLARE @string as nvarchar(max) -- 源字符串,子串间用分隔符隔开
 --DECLARE @spchar as char(1)         -- 分隔符
 --DECLARE @strlen INT
 --DECLARE @eachstrEnoughLenStartIndex INT
 --DECLARE @eachstrEnoughLenEndIndex INT
 --DECLARE @eachstrNotEnoughLenStartIndex INT
 --DECLARE @eachstrNotEnoughLenEndIndex INT

 --SET @spchar=',' -- 分隔符
 --SET @string='CJ2249301801,CJ2249300803,CJ2249301901,CJ2249302003' 
 --SET @strlen=12
 --SET @eachstrEnoughLenStartIndex=6
 --SET @eachstrEnoughLenEndIndex=3
 --SET @eachstrNotEnoughLenStartIndex=1
 --SET @eachstrNotEnoughLenEndIndex=3

 DECLARE @startIndex as int         -- 起点
 DECLARE @endIndex as int         -- 结束点
 DECLARE @log as nvarchar(max)     -- 执行记录
 DECLARE @count as int             -- 查找次数
 -- 源字符串,起点不包含分隔符,结束包含分隔符
 SET @startIndex=0 -- 0位置为初起点
 SET @log=''
 SET @count=1
 SELECT @endIndex=CHARINDEX(@spchar,@string);-- 第1个分隔符位置为结束点
 -- charindex找不到字符串时,返回0.循环成立条件是能找到分隔符
 WHILE @endIndex>0
 BEGIN
	 DECLARE @subStr as nvarchar(20) -- 子字符串
	 -- 根据起止点及起止点之差为长度找出子字符串
	 SELECT @subStr=SUBSTRING(@string,@startIndex,@endIndex-@startIndex)
	 -- 下一起点为当前止点加1
	 SET @startIndex=@endIndex+1
	 -- 查找下一分隔符位置,即新的止点
	 SET @endIndex=CHARINDEX(@spchar,@string,@startIndex);

	 IF LEN(@subStr)>=@strlen
	BEGIN
		SET @subStr=SUBSTRING(@subStr,@eachstrEnoughLenStartIndex,@eachstrEnoughLenEndIndex)
	END;
	ELSE
	BEGIN
		SET @subStr=SUBSTRING(@subStr,@eachstrNotEnoughLenStartIndex,@eachstrNotEnoughLenEndIndex)
	END;
	 IF @count=1
	 BEGIN
		SET @log=@log+@subStr
	 END;
	 ELSE
	 BEGIN
		SET @log=@log+@spchar+@subStr
	 END;
 
	 SET @count=@count+1
 END
 RETURN @log

END;