Replace a newline in TSQL

Actually a new line in a SQL command or script string can be any of CR, LF or CR+LF. To get them all, you need something like this:

SELECT REPLACE(REPLACE(@str, CHAR(13), ''), CHAR(10), '')

REPLACE(@string, CHAR(13) + CHAR(10), '')

I may be a year late to the party, but I work on queries & MS-SQL every day, and I got tired of the built-in functions 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 whitespace) extended forms of whitespace (tab, line-feed, carriage-return, etc.), so it's been renamed as "CleanAndTrim" from my original answer. The idea here is that your string doesn't need such extra special-whitespace 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_CleanAndTrim] (
       @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

Cheers!

Another Disclaimer: Your typical Windows line-break is CR+LF, so if your string contains those, you'd end up replacing them with "double" spaces.

UPDATE, 2016: A new version that gives you the option to replace those special-whitespace characters with other characters of your choice! This also includes commentary and the work-around for the Windows CR+LF pairing, i.e. replaces that specific char-pair with a single substitution.

IF OBJECT_ID('dbo.fn_CleanAndTrim') IS NULL
    EXEC ('CREATE FUNCTION dbo.fn_CleanAndTrim () 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_CleanAndTrim] (
    @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