January 18, 2011 at 5:02 pm
I have the following code that I'm trying to implement. I have a successful solution using SQL CLR but the project team consensus is to keep everything within SQL Server as a stored proc or function, etc.
Description of problem: Simply need to globally parse the 4 digit variables from a string--example string is as follow:
(4523, 6734, 7895, etc)
My existing code is as follow:
(Note, the code returns a numeric value of 1; I would expect it to return the four digit values sequentially, therefore, I can do something with each returned value.)
CREATE FUNCTION [dbo].[GetMyPPECode]
(
@pattern VARCHAR(2000),
@matchstring VARCHAR(MAX)
)
RETURNS VARCHAR
AS BEGIN
DECLARE @objRegexExp INT,
@objErrorObject INT,
@strErrorMessage VARCHAR(255),
@hr INT,
@match BIT
SELECT @strErrorMessage = 'creating a regex object'
EXEC @hr= sp_OACreate 'VBScript.RegExp', @objRegexExp OUTPUT
IF @hr = 0
EXEC @hr= sp_OASetProperty @objRegexExp, 'Pattern', @pattern
IF @hr = 0
EXEC @hr= sp_OASetProperty @objRegexExp, 'IgnoreCase', 1
IF @hr = 0
EXEC @hr = sp_OASetProperty @objRegexExp, 'Global', true
IF @hr = 0
EXEC @hr = sp_OASetProperty @objRegexExp, 'Multiline', true
IF @hr = 0
EXEC @hr= sp_OAMethod @objRegexExp, 'Test', @match OUTPUT, @matchstring
IF @hr <> 0
BEGIN
RETURN NULL
END
EXEC sp_OADestroy @objRegexExp
RETURN @match
END
SELECT dbo.GetMyPPECode('\d{4}','3435, 2134, 6578')
--This returns a value of one; I need it to return the values as
3435
2134
6578
Any help would be appreciated
January 18, 2011 at 8:55 pm
The following should help. Be advised that a revision to make it faster for higher byte counts is in the works must not much will touch it for strings up to a couple of thousand bytes. The documentation is significantly longer than the actual code so don't be afraid of it's apparent length...
DROP FUNCTION dbo.DelimitedSplit8K
GO
CREATE FUNCTION dbo.DelimitedSplit8K
/***************************************************************************************************
Purpose:
Split a given string at a given delimiter and return a list of the split elements (items).
Returns:
iTVF containing the following:
ItemNumber = Element position of Item as a BIGINT (not converted to INT to eliminate a CAST)
Item = Element value as a VARCHAR(8000)
CROSS APPLY Usage Example:
---------------------------------------------------------------------------------------------------
--===== Conditionally drop the test tables to make reruns easier for testing.
-- (this is NOT a part of the solution)
IF OBJECT_ID('tempdb..#JBMTest') IS NOT NULL
DROP TABLE #JBMTest
;
--===== Create and populate a test table on the fly (this is NOT a part of the solution).
SELECT *
INTO #JBMTest
FROM (
SELECT 1,'1,10,100,1000,10000,100000,1000000' UNION ALL
SELECT 2,'2000000,200000,20000,2000,200,20,2' UNION ALL
SELECT 3, 'This,is,a,test' UNION ALL
SELECT 4, 'and so is this' UNION ALL
SELECT 5, 'This, too (no pun intended)'
) d (SomeID,SomeValue)
;
GO
--===== Split the CSV column for the whole table using CROSS APPLY (this is the solution)
SELECT test.SomeID, split.ItemNumber, split.Item
FROM #JBMTest test
CROSS APPLY
(
SELECT ItemNumber, Item
FROM dbo.DelimitedSplit8k(test.SomeValue,',')
) split
;
---------------------------------------------------------------------------------------------------
Notes:
1. Optimized for VARCHAR(7999) or less. No testing or error reporting for truncation at 7999
characters is done.
2. Optimized for single character delimiter. Multi-character delimiters should be resolved
externally from this function.
3. Optimized for use with CROSS APPLY.
4. Does not "trim" elements just in case leading or trailing blanks are intended.
5. If you don't know how a Tally table can be used to replace loops, please see the following...
http://www.sqlservercentral.com/articles/T-SQL/62867/
6. Changing this function to use VARCHAR(MAX) will cause it to run twice as slow. It's just the
nature of VARCHAR(MAX) whether it fits in-row or not.
7. Multi-machine testing for the method of using UNPIVOT instead of 10 SELECT/UNION ALLs shows
that the UNPIVOT method is quite machine dependent and can slow things down quite a bit.
8. Performance testing shows using "TOP" for the limiting criteria of "N" is actually
slower and slightly more CPU intensive than the traditional WHERE N < LEN(@pString) + 2.
9. Performance testing shows using ORDER BY (SELECT x) where "x" is anything is actually
slower and slightly more CPU intensive than the traditional ORDER BY (SELECT N).
Credits:
This code is the product of many people's efforts including but not limited to the following:
cteTally concept originally by Iztek Ben Gan and "decimalized" by Lynn Pettis (and others) for a
bit of extra speed and finally redacted by Jeff Moden for a different slant on readability and
compactness. Hat's off to Paul White for his simple explanations of CROSS APPLY. Finally,
special thanks to Erland Sommarskog for his tireless efforts to help people understand
what you can actually do with T-SQL. I also thank whoever wrote the first article I ever saw
on "numbers tables" which is located at the following URL ...
http://sqlserver2000.databases.aspfaq.com/why-should-i-consider-using-an-auxiliary-numbers-table.html
Revision History:
Rev 00 - 20 Jan 2010 - Concept: Lynn Pettis and others.
Redaction/Implementation: Jeff Moden
- Base 10 redaction and reduction for CTE. (Total rewrite)
Rev 01 - 13 Mar 2010 - Jeff Moden
- Removed one additional concatenation and one subtraction from the SUBSTRING in the
SELECT List for that tiny bit of extra speed.
Rev 02 - 14 Apr 2010 - Jeff Moden
- No code changes. Added CROSS APPLY usage example to the header, some additional credits,
and extra documentation.
Rev 03 - 18 Apr 2010 - Jeff Moden
- No code changes. Added notes 7, 8, and 9 about certain "optimizations" that dont'
actually work for this type of function.
Rev 04 - 29 Jun 2010 - Jeff Moden
- Added WITH SCHEMABINDING thanks to a note by Paul White. This prevents an unnecessary
"Table Spool" when the function is used in an UPDATE statement even though the function
makes no external references.
***************************************************************************************************/
--===== Define I/O parameters
(
@pString VARCHAR(7999),
@pDelimiter CHAR(1)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
--===== "Inline" CTE Driven "Tally Table” produces values up to
-- 10,000... enough to cover VARCHAR(8000)
WITH
E1(N) AS ( --=== Create Ten 1's
SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 --10
),
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --100
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10,000
cteTally(N) AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT N)) FROM E4)
--===== Do the split
SELECT ROW_NUMBER() OVER (ORDER BY N) AS ItemNumber,
SUBSTRING(@pString, N, CHARINDEX(@pDelimiter, @pString + @pDelimiter, N) - N) AS Item
FROM cteTally
WHERE N <= DATALENGTH(@pString)+1 --DATATLENGTH allows for trailing space delimiters
AND SUBSTRING(@pDelimiter + @pString, N, 1) = @pDelimiter
;
GO
--Jeff Moden
Change is inevitable... Change for the better is not.
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