Sql server 2008 获取两个字符串之间的字符串-SQL Server

我得到了一个返回两个字符串之间字符串的函数：

CREATE FUNCTION dbo.udf_GetStringBetween2Chars (@String VARCHAR(50), @FirstSpecialChar VARCHAR(50), @LastSpecialChar VARCHAR(50))
RETURNS VARCHAR(50)
AS
BEGIN
   DECLARE @FirstIndexOfChar INT,
         @LastIndexOfChar INT,
         @LengthOfStringBetweenChars INT 

   SET @FirstIndexOfChar   = CHARINDEX(@FirstSpecialChar,@String,0) 
   SET @LastIndexOfChar   = CHARINDEX(@LastSpecialChar,@String,@FirstIndexOfChar+1)
   SET @LengthOfStringBetweenChars = @LastIndexOfChar - @FirstIndexOfChar -1

   SET @String = SUBSTRING(@String,@FirstIndexOfChar+1,@LengthOfStringBetweenChars)

   RETURN @String
END

但是，当我尝试获取POINTDESCRIPTION和DATAPOINT之间的字符串时，我得到错误：

SET ANSI_WARNINGS OFF
declare @table table 
(string varchar(50))

insert into @table
select 'EVENT: ID Order Reassignment (Individual Job Specific Update)|||LOCATION: Reassign.reassign()|||DATEPOINTDESCRIPTION: Only specific ID orders were reassigned from user fatis to user blake.|||DATAPOINT: blake' union all
select 'EVENT: ID Order Reassignment (Individual Job Specific Update)|||LOCATION: Reassign.reassign()|||DATAPOINTDESCRIPTION: Only specific ID orders were reassigned from user ilevic to user manic2.|||DATAPOINT: manic2' union all
select 'EVENT: ID Order Reassignment (Individual Job Specific Update)|||LOCATION: Reassign.reassign()|||DATAPOINTDESCRIPTION: Only specific ID orders were reassigned from user links to user sepir.|||DATAPOINT: sepir'
select dbo.udf_GetStringBetween2Chars (Tab.string,'POINTDESCRIPTION: ','|||DATAPOINT')
FROM @table Tab

Msg 537, Level 16, State 2, Line 10
    Invalid length parameter passed to the LEFT or SUBSTRING function.

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有人知道为什么会发生这种情况吗？

如果有人觉得它有用，下面是返回两个字符串之间字符串的最后一个函数：

CREATE FUNCTION dbo.udf_GetStringBetween2Chars (@String VARCHAR(500), @FirstSpecialChar VARCHAR(500), @LastSpecialChar VARCHAR(500))
RETURNS VARCHAR(500)
AS
BEGIN
   DECLARE @FirstIndexOfChar INT,
         @LastIndexOfChar INT,
         @LengthOfStringBetweenChars INT 
   SET @FirstIndexOfChar   = CHARINDEX(@FirstSpecialChar,@String,0) 
   SET @LastIndexOfChar   = CHARINDEX(@LastSpecialChar,@String,@FirstIndexOfChar+1)
   SET @LengthOfStringBetweenChars = @LastIndexOfChar - @FirstIndexOfChar -1
   SET @String = SUBSTRING(@String,@FirstIndexOfChar+LEN(@FirstSpecialChar),@LengthOfStringBetweenChars)
   RETURN @String
END
GO

并称之为：

select dbo.udf_GetStringBetween2Chars (tab.someString,'POINTDESCRIPTION: ','|||DATAPOINT')
FROM yourTable tab

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我的坏：/I我通过增加temp table中字符串的长度来修复它：declare@table table（string varchar（500））哈哈，每次我都会这样！我确实注意到了我的函数中的一个缺陷：设置@FirstIndexOfChar=CHARINDEX（@FirstSpecialChar，@String，0），我想零应该是第一个找到的字符的长度。不需要。