Wednesday, November 18, 2009

T-SQL Split

I still have seen developer asking me how to Split in SQL Server, although we can enable CLR Integration in SQL Server, here is the classic one from SQL Server Magazine that I have used since SQL Server 2000 and it is very powerful, Treat Yourself to Fn_Split() - This UDF lets you emulate VB's Split() function and parameter arrays

CREATE FUNCTION fn_Split(@sText varchar(8000), @sDelim varchar(20) = ' ')
RETURNS @retArray TABLE (idx smallint Primary Key, value varchar(8000))
AS
BEGIN
DECLARE @idx smallint,
@value varchar(8000),
@bcontinue bit,
@iStrike smallint,
@iDelimlength tinyint

IF @sDelim = 'Space'
BEGIN
SET @sDelim = ' '
END

SET @idx = 0
SET @sText = LTrim(RTrim(@sText))
SET @iDelimlength = DATALENGTH(@sDelim)
SET @bcontinue = 1

IF NOT ((@iDelimlength = 0) or (@sDelim = 'Empty'))
BEGIN
WHILE @bcontinue = 1
BEGIN

--If you can find the delimiter in the text, retrieve the first element and
--insert it with its index into the return table.

IF CHARINDEX(@sDelim, @sText)>0
BEGIN
SET @value = SUBSTRING(@sText,1, CHARINDEX(@sDelim,@sText)-1)
BEGIN
INSERT @retArray (idx, value)
VALUES (@idx, @value)
END

--Trim the element and its delimiter from the front of the string.
--Increment the index and loop.
SET @iStrike = DATALENGTH(@value) + @iDelimlength
SET @idx = @idx + 1
SET @sText = LTrim(Right(@sText,DATALENGTH(@sText) - @iStrike))

END
ELSE
BEGIN
--If you can抰 find the delimiter in the text, @sText is the last value in
--@retArray.
SET @value = @sText
BEGIN
INSERT @retArray (idx, value)
VALUES (@idx, @value)
END
--Exit the WHILE loop.
SET @bcontinue = 0
END
END
END
ELSE
BEGIN
WHILE @bcontinue=1
BEGIN
--If the delimiter is an empty string, check for remaining text
--instead of a delimiter. Insert the first character into the
--retArray table. Trim the character from the front of the string.
--Increment the index and loop.
IF DATALENGTH(@sText)>1
BEGIN
SET @value = SUBSTRING(@sText,1,1)
BEGIN
INSERT @retArray (idx, value)
VALUES (@idx, @value)
END
SET @idx = @idx+1
SET @sText = SUBSTRING(@sText,2,DATALENGTH(@sText)-1)

END
ELSE
BEGIN
--One character remains.
--Insert the character, and exit the WHILE loop.
INSERT @retArray (idx, value)
VALUES (@idx, @sText)
SET @bcontinue = 0 
END
END

END

RETURN
END
GO

-- Sample Code for Using Fn_Split() in Pubs to Emulate a Parameter Array

Use Pubs

CREATE  PROCEDURE procPubsTitleView

@sAuthors varchar(8000)
AS
SELECT title, au_lname, price FROM Pubs.dbo.titleview
JOIN dbo.fn_Split(@sAuthors, ',') 
ON au_lname = value
RETURN
GO