SQL Server: How do you remove punctuation from a field? - sql

Question

Any one know a good way to remove punctuation from a field in SQL Server?
I'm thinking
UPDATE tblMyTable SET FieldName = REPLACE(REPLACE(REPLACE(FieldName,',',''),'.',''),'''' ,'')
but it seems a bit tedious when I intend on removing a large number of different characters for example: !##$%^&*()<>:"
Thanks in advance

Answer 1

Ideally, you would do this in an application language such as C# + LINQ as mentioned above.
If you wanted to do it purely in T-SQL though, one way make things neater would be to firstly create a table that held all the punctuation you wanted to removed.
CREATE TABLE Punctuation
(
Symbol VARCHAR(1) NOT NULL
)
INSERT INTO Punctuation (Symbol) VALUES('''')
INSERT INTO Punctuation (Symbol) VALUES('-')
INSERT INTO Punctuation (Symbol) VALUES('.')
Next, you could create a function in SQL to remove all the punctuation symbols from an input string.
CREATE FUNCTION dbo.fn_RemovePunctuation
(
#InputString VARCHAR(500)
)
RETURNS VARCHAR(500)
AS
BEGIN
SELECT
#InputString = REPLACE(#InputString, P.Symbol, '')
FROM
Punctuation P
RETURN #InputString
END
GO
Then you can just call the function in your UPDATE statement
UPDATE tblMyTable SET FieldName = dbo.fn_RemovePunctuation(FieldName)

Answer 2

I wanted to avoid creating a table and wanted to remove everything except letters and digits.
DECLARE #p int
DECLARE #Result Varchar(250)
DECLARE #BadChars Varchar(12)
SELECT #BadChars = '%[^a-z0-9]%'
-- to leave spaces - SELECT #BadChars = '%[^a-z0-9] %'
SET #Result = #InStr
SET #P =PatIndex(#BadChars,#Result)
WHILE #p > 0 BEGIN
SELECT #Result = Left(#Result,#p-1) + Substring(#Result,#p+1,250)
SET #P =PatIndex(#BadChars,#Result)
END

Answer 3

I am proposing 2 solutions
Solution 1: Make a noise table and replace the noises with blank spaces
e.g.
DECLARE #String VARCHAR(MAX)
DECLARE #Noise TABLE(Noise VARCHAR(100),ReplaceChars VARCHAR(10))
SET #String = 'hello! how * > are % u (: . I am ok :). Oh nice!'
INSERT INTO #Noise(Noise,ReplaceChars)
SELECT '!',SPACE(1) UNION ALL SELECT '#',SPACE(1) UNION ALL
SELECT '#',SPACE(1) UNION ALL SELECT '$',SPACE(1) UNION ALL
SELECT '%',SPACE(1) UNION ALL SELECT '^',SPACE(1) UNION ALL
SELECT '&',SPACE(1) UNION ALL SELECT '*',SPACE(1) UNION ALL
SELECT '(',SPACE(1) UNION ALL SELECT ')',SPACE(1) UNION ALL
SELECT '{',SPACE(1) UNION ALL SELECT '}',SPACE(1) UNION ALL
SELECT '<',SPACE(1) UNION ALL SELECT '>',SPACE(1) UNION ALL
SELECT ':',SPACE(1)
SELECT #String = REPLACE(#String, Noise, ReplaceChars) FROM #Noise
SELECT #String Data
Solution 2: With a number table
DECLARE #String VARCHAR(MAX)
SET #String = 'hello! & how * > are % u (: . I am ok :). Oh nice!'
;with numbercte as
(
select 1 as rn
union all
select rn+1 from numbercte where rn<LEN(#String)
)
select REPLACE(FilteredData,' ',SPACE(1)) Data from
(select SUBSTRING(#String,rn,1)
from numbercte
where SUBSTRING(#String,rn,1) not in('!','*','>','<','%','(',')',':','!','&','#','#','$')
for xml path(''))X(FilteredData)
Output(Both the cases)
Data
hello how are u . I am ok . Oh nice
Note- I have just put some of the noises. You may need to put the noises that u need.
Hope this helps

Answer 4

You can use regular expressions in SQL Server - here is an article based on SQL 2005:
http://msdn.microsoft.com/en-us/magazine/cc163473.aspx

Answer 5

I'd wrap it in a simple scalar UDF so all string cleaning is in one place if it's needed again.
Then you can use it on INSERT too...

Answer 6

I took Ken MC's solution and made it into an function which can replace all punctuation with a given string:
----------------------------------------------------------------------------------------------------------------
-- This function replaces all punctuation in the given string with the "replaceWith" string
----------------------------------------------------------------------------------------------------------------
IF object_id('[dbo].[fnReplacePunctuation]') IS NOT NULL
BEGIN
DROP FUNCTION [dbo].[fnReplacePunctuation];
END;
GO
CREATE FUNCTION [dbo].[fnReplacePunctuation] (#string NVARCHAR(MAX), #replaceWith NVARCHAR(max))
RETURNS NVARCHAR(MAX)
BEGIN
DECLARE #Result Varchar(max) = #string;
DECLARE #BadChars Varchar(12) = '%[^a-z0-9]%'; -- to leave spaces - SELECT #BadChars = '%[^a-z0-9] %'
DECLARE #p int = PatIndex(#BadChars,#Result);
DECLARE #searchFrom INT;
DECLARE #indexOfPunct INT = #p;
WHILE #indexOfPunct > 0 BEGIN
SET #searchFrom = LEN(#Result) - #p;
SET #Result = Left(#Result, #p-1) + #replaceWith + Substring(#Result, #p+1,LEN(#Result));
SET #IndexOfPunct = PatIndex(#BadChars, substring(#Result, (LEN(#Result) - #SearchFrom)+1, LEN(#Result)));
SET #p = (LEN(#Result) - #searchFrom) + #indexOfPunct;
END
RETURN #Result;
END;
GO
-- example:
SELECT dbo.fnReplacePunctuation('This is, only, a tést-really..', '');
Output:
Thisisonlyatéstreally

Answer 7

If it's a one-off thing, I would use a C# + LINQ snippet in LINQPad to do the job with regular expressions.
It is quick and easy and you don't have to go through the process of setting up a CLR stored procedure and then cleaning up after yourself.

Answer 8

Can't you use PATINDEX to only include NUMBERS and LETTERS instead of trying to guess what punctuation might be in the field? (Not trying to be snarky, if I had the code ready, I'd share it...but this is what I'm looking for).
Seems like you need to create a custom function in order to avoid a giant list of replace functions in your queries - here's a good example:
http://www.codeproject.com/KB/database/SQLPhoneNumbersPart_2.aspx?display=Print