Add a TRIM for LTRIM/RTRIM

LTRIM() & RTRIM() (and always having to call them together), and of not catching 'dirty' data that had newlines at the

--end, so I decided it was high time to implement a better TRIM function. I'd welcome peer feedback!

--Disclaimer: this actually removes (replaces with a single white space) extended forms of white space (tab, line-feed, carriage-return, etc.), 

--The idea here is that your string doesn't need such extra special-white space characters inside it, and so

--if they don't occur at the head/tail, they should be replaced with a plain space. If you purposefully stored

--such characters in your string (say, your column of data that you're about to run this on), 

--DON'T DO IT! Improve this function or write your own that literally just removes those characters

--from the endpoints of the string, not from the 'body'.

--Okay, now that the disclaimer is updated, here's the code.

-- =============================================

-- Description: TRIMs a string 'for real' - removes standard whitespace from ends,

-- and replaces ASCII-char's 9-13, which are tab, line-feed, vert tab,

-- form-feed, & carriage-return (respectively), with a whitespace

-- (and then trims that off if it's still at the beginning or end, of course).

-- =============================================

CREATE FUNCTION [fn_CleanTrim] (

       @Str nvarchar(max)

)

RETURNS nvarchar(max) AS

BEGIN

       DECLARE @Result nvarchar(max)

       SET @Result = LTRIM(RTRIM(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(

              LTRIM(RTRIM(@Str)), CHAR(9), ' '), CHAR(10), ' '), CHAR(11), ' '), CHAR(12), ' '), CHAR(13), ' ')))

       RETURN @Result

END

IF OBJECT_ID('dbo.fn_CleanAndTrim') IS NULL

    EXEC ('CREATE FUNCTION dbo.fn_CleanTrim () RETURNS INT AS BEGIN RETURN 0 END')

GO

-- =============================================

-- Author: Nate Johnson

-- Source: http://stackoverflow.com/posts/24068265

-- Description: TRIMs a string 'for real' - removes standard whitespace from ends,

-- and replaces ASCII-char's 9-13, which are tab, line-feed, vert tab, form-feed,

-- & carriage-return (respectively), with a whitespace or specified character(s).

-- Option "@PurgeReplaceCharsAtEnds" determines whether or not to remove extra head/tail

-- replacement-chars from the string after doing the initial replacements.

-- This is only truly useful if you're replacing the special-chars with something

-- **OTHER** than a space, because plain LTRIM/RTRIM will have already removed those.

-- =============================================

ALTER FUNCTION dbo.[fn_CleanTrim] (

    @Str NVARCHAR(MAX)

    , @ReplaceTabWith NVARCHAR(5) = ' '

    , @ReplaceNewlineWith NVARCHAR(5) = ' '

    , @PurgeReplaceCharsAtEnds BIT = 1

)

RETURNS NVARCHAR(MAX) AS

BEGIN

    DECLARE @Result NVARCHAR(MAX)

    --The main work (trim & initial replacements)

    SET @Result = LTRIM(RTRIM(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(

        LTRIM(RTRIM(@Str))  --Basic trim

        , NCHAR(9), @ReplaceTabWith), NCHAR(11), @ReplaceTabWith)   --Replace tab & vertical-tab

        , (NCHAR(13) + NCHAR(10)), @ReplaceNewlineWith) --Replace "Windows" linebreak (CR+LF)

        , NCHAR(10), @ReplaceNewlineWith), NCHAR(12), @ReplaceNewlineWith), NCHAR(13), @ReplaceNewlineWith)))   --Replace other newlines

    --If asked to trim replacement-char's from the ends & they're not both whitespaces

    IF (@PurgeReplaceCharsAtEnds = 1 AND NOT (@ReplaceTabWith = N' ' AND @ReplaceNewlineWith = N' '))

    BEGIN

        --Purge from head of string (beginning)

        WHILE (LEFT(@Result, DATALENGTH(@ReplaceTabWith)/2) = @ReplaceTabWith)

            SET @Result = SUBSTRING(@Result, DATALENGTH(@ReplaceTabWith)/2 + 1, DATALENGTH(@Result)/2)

        WHILE (LEFT(@Result, DATALENGTH(@ReplaceNewlineWith)/2) = @ReplaceNewlineWith)

            SET @Result = SUBSTRING(@Result, DATALENGTH(@ReplaceNewlineWith)/2 + 1, DATALENGTH(@Result)/2)

        --Purge from tail of string (end)

        WHILE (RIGHT(@Result, DATALENGTH(@ReplaceTabWith)/2) = @ReplaceTabWith)

            SET @Result = SUBSTRING(@Result, 1, DATALENGTH(@Result)/2 - DATALENGTH(@ReplaceTabWith)/2)

        WHILE (RIGHT(@Result, DATALENGTH(@ReplaceNewlineWith)/2) = @ReplaceNewlineWith)

            SET @Result = SUBSTRING(@Result, 1, DATALENGTH(@Result)/2 - DATALENGTH(@ReplaceNewlineWith)/2)

    END

    RETURN @Result

END

GO