How to remove special characters like TAB, Carriage Return, and Line Feed characters from string in SQL Server

Today, we are going to see a scenario where we need to remove special characters from a string in SQL Server. Let us discuss on few methods to achieve this “extended” trim functionality.

1. Option: Using REPLACE

REPLACE function can be effectively used to replace the special characters.

Script:

DECLARE @BaddataString NVARCHAR(max);
SET @BaddataString = 'my '+
			CHAR(10)+CHAR(10)+CHAR(10) +
			 'text   ' + 
			CHAR(9)+CHAR(10)+CHAR(13)+CHAR(32) + 
			 '     ' +
			CHAR(10)+CHAR(10)+CHAR(10);

SELECT 
           @BaddataString,
           LEN(@BaddataString)
           , REPLACE(REPLACE(REPLACE(RTRIM(@BaddataString),CHAR(9), ''),CHAR(10),''),CHAR(13),'') ,
           LEN(REPLACE(REPLACE(REPLACE(RTRIM(@BaddataString),CHAR(9), ''),CHAR(10),''),CHAR(13),''))


Here is the output of the below code:

2. Option: Using CDATA Another effective option to use CDATA method.

Script


/*
The below function replaces special characters like invisible TAB, Carriage Return, and Line Feed characters.
*/
CREATE FUNCTION dbo.FN_RemoveBadCharacter(@input VARCHAR(MAX))
   RETURNS VARCHAR(MAX)
AS
BEGIN 
   RETURN (SELECT CAST('' AS XML).value('(/r/text())[1] cast as xs:token?','VARCHAR(MAX)'));
END
GO
DECLARE @BaddataString NVARCHAR(max);
SET @BaddataString = 'my '+
						CHAR(10)+CHAR(10)+CHAR(10) +
					 'text   ' + 
						CHAR(9)+CHAR(10)+CHAR(13)+CHAR(32) + 
					 '     ' +
						CHAR(10)+CHAR(10)+CHAR(10);

SELECT		@BaddataString, 
		LEN(@BaddataString)
			, dbo.FN_RemoveBadCharacter(@BaddataString),
		LEN(dbo.FN_RemoveBadCharacter(@BaddataString))

Here is the output of the below code:

3. Option: Using CLR to define a function to remove

There are certain things its best to do at application code rather than T-SQL. SQL Server may not be the best place to formatting string, date etc. There will be lots of available resources just away from a google search.

Hope, you enjoy this post, please share your thoughts as always!

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