March 21, 2012 at 4:22 pm
Hello All,
I want to extract all characters between the first and second dash.
The below seems to work but I would be happy if someone could provide a simpler more robust way of doing this.
CREATE TABLE #Test (TestColumn varchar (24))
INSERT INTO #Test
SELECT '123-3456-789-987-65' UNION
SELECT '223-13446-789-987-65' UNION
SELECT '323-16-789-987-65' UNION
SELECT '423-45454516-789-987-65'
SELECT
LEFT
(
RIGHT(TestColumn,(LEN(TestColumn)-CHARINDEX('-',TestColumn)))
,
(CHARINDEX('-',RIGHT(TestColumn,(LEN(TestColumn)-CHARINDEX('-',TestColumn))))-1)
)
FROM #Test
SELECT * FROM #Test
DROP TABLE #Test
March 21, 2012 at 4:33 pm
Similar to yours, but with one CHARINDEX and all LEN removed
CRAP CODE 😀
March 21, 2012 at 4:37 pm
Very similar to yours!
SELECT LEFT ( CrsApp.CtStr , CHARINDEX('-',CrsApp.CtStr) -1 )
FROM #Test T1
CROSS APPLY (SELECT STUFF ( T1.TestColumn , 1 , CHARINDEX('-',T1.TestColumn),'') ) CrsApp (CtStr)
March 21, 2012 at 5:27 pm
Here is another way to do it:
CREATE TABLE #Test (TestColumn varchar (24))
INSERT INTO #Test
SELECT '123-3456-789-987-65' UNION
SELECT '223-13446-789-987-65' UNION
SELECT '323-16-789-987-65' UNION
SELECT '423-45454516-789-987-65'
select * from #Test;
select
t.TestColumn,
ds.item
from
#Test t
cross apply dbo.DelimitedSplit8K(t.TestColumn, '-') ds
where
ds.ItemNumber = 2;
drop table #Test;
Here is the dbo.DelimitedSplit8K function:
USE [Sandbox]
GO
/****** Object: UserDefinedFunction [dbo].[DelimitedSplit8K] Script Date: 03/21/2012 17:24:54 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE FUNCTION [dbo].[DelimitedSplit8K]
/**********************************************************************************************************************
Purpose:
Split a given string at a given delimiter and return a list of the split elements (items).
Notes:
1. Leading a trailing delimiters are treated as if an empty string element were present.
2. Consecutive delimiters are treated as if an empty string element were present between them.
3. Except when spaces are used as a delimiter, all spaces present in each element are preserved.
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)
Statistics on this function may be found at the following URL:
http://www.sqlservercentral.com/Forums/Topic1101315-203-4.aspx
CROSS APPLY Usage Examples and Tests:
--=====================================================================================================================
-- TEST 1:
-- This tests for various possible conditions in a string using a comma as the delimiter. The expected results are
-- laid out in the comments
--=====================================================================================================================
--===== 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).
-- In the following comments, "b" is a blank and "E" is an element in the left to right order.
-- Double Quotes are used to encapsulate the output of "Item" so that you can see that all blanks
-- are preserved no matter where they may appear.
SELECT *
INTO #JBMTest
FROM ( --# & type of Return Row(s)
SELECT 0, NULL UNION ALL --1 NULL
SELECT 1, SPACE(0) UNION ALL --1 b (Empty String)
SELECT 2, SPACE(1) UNION ALL --1 b (1 space)
SELECT 3, SPACE(5) UNION ALL --1 b (5 spaces)
SELECT 4, ',' UNION ALL --2 b b (both are empty strings)
SELECT 5, '55555' UNION ALL --1 E
SELECT 6, ',55555' UNION ALL --2 b E
SELECT 7, ',55555,' UNION ALL --3 b E b
SELECT 8, '55555,' UNION ALL --2 b B
SELECT 9, '55555,1' UNION ALL --2 E E
SELECT 10, '1,55555' UNION ALL --2 E E
SELECT 11, '55555,4444,333,22,1' UNION ALL --5 E E E E E
SELECT 12, '55555,4444,,333,22,1' UNION ALL --6 E E b E E E
SELECT 13, ',55555,4444,,333,22,1,' UNION ALL --8 b E E b E E E b
SELECT 14, ',55555,4444,,,333,22,1,' UNION ALL --9 b E E b b E E E b
SELECT 15, ' 4444,55555 ' UNION ALL --2 E (w/Leading Space) E (w/Trailing Space)
SELECT 16, 'This,is,a,test.' --E E E E
) d (SomeID, SomeValue)
;
--===== Split the CSV column for the whole table using CROSS APPLY (this is the solution)
SELECT test.SomeID, test.SomeValue, split.ItemNumber, Item = QUOTENAME(split.Item,'"')
FROM #JBMTest test
CROSS APPLY dbo.DelimitedSplit8K(test.SomeValue,',') split
;
--=====================================================================================================================
-- TEST 2:
-- This tests for various "alpha" splits and COLLATION using all ASCII characters from 0 to 255 as a delimiter against
-- a given string. Note that not all of the delimiters will be visible and some will show up as tiny squares because
-- they are "control" characters. More specifically, this test will show you what happens to various non-accented
-- letters for your given collation depending on the delimiter you chose.
--=====================================================================================================================
WITH
cteBuildAllCharacters (String,Delimiter) AS
(
SELECT TOP 256
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',
CHAR(ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1)
FROM master.sys.all_columns
)
SELECT ASCII_Value = ASCII(c.Delimiter), c.Delimiter, split.ItemNumber, Item = QUOTENAME(split.Item,'"')
FROM cteBuildAllCharacters c
CROSS APPLY dbo.DelimitedSplit8K(c.String,c.Delimiter) split
ORDER BY ASCII_Value, split.ItemNumber
;
-----------------------------------------------------------------------------------------------------------------------
Other Notes:
1. Optimized for VARCHAR(8000) or less. No testing or error reporting for truncation at 8000 characters is done.
2. Optimized for single character delimiter. Multi-character delimiters should be resolvedexternally 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 NVARCHAR(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.
-----------------------------------------------------------------------------------------------------------------------
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 and for his detailed testing efforts. Last but not least, thanks to
Ron "BitBucket" McCullough and Wayne Sheffield for their extreme performance testing across multiple machines and
versions of SQL Server. The latest improvement brought an additional 15-20% improvement over Rev 05. Special thanks
to "Nadrek" and "peter-757102" (aka Peter de Heer) for bringing such improvements to light. Nadrek's original
improvement brought about a 10% performance gain and Peter followed that up with the content of Rev 07.
I also thank whoever wrote the first article I ever saw on "numbers tables" which is located at the following URL
and to Adam Machanic for leading me to it many years ago.
-----------------------------------------------------------------------------------------------------------------------
Revision History:
Rev 00 - 20 Jan 2010 - Concept for inline cteTally: 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 don't 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.
Rev 05 - 02 Apr 2011 - Jeff Moden
- Rewritten for extreme performance improvement especially for larger strings approaching the 8K boundary and
for strings that have wider elements. The redaction of this code involved removing ALL concatenation of
delimiters, optimization of the maximum "N" value by using TOP instead of including it in the WHERE clause,
and the reduction of all previous calculations (thanks to the switch to a "zero based" cteTally) to just one
instance of one add and one instance of a subtract. The length calculation for the final element (not
followed by a delimiter) in the string to be split has been greatly simplified by using the ISNULL/NULLIF
combination to determine when the CHARINDEX returned a 0 which indicates there are no more delimiters to be
had or to start with. Depending on the width of the elements, this code is between 4 and 8 times faster on a
single CPU box than the original code especially near the 8K boundary.
- Modified comments to include more sanity checks on the usage example, etc.
- Removed "other" notes 8 and 9 as they were no longer applicable.
Rev 06 - 12 Apr 2011 - Jeff Moden
- Based on a suggestion by Ron "Bitbucket" McCullough, additional test rows were added to the sample code and
the code was changed to encapsulate the output in pipes so that spaces and empty strings could be perceived
in the output. The first "Notes" section was added. Finally, an extra test was added to the comments above.
Rev 07 - 06 May 2011 - Peter de Heer, a further 15-20% performance enhancement has been discovered and incorporated
into this code which also eliminated the need for a "zero" position in the cteTally table.
**********************************************************************************************************************/
--===== Define I/O parameters
(@pString VARCHAR(8000), @pDelimiter CHAR(1))
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
-- enough to cover NVARCHAR(4000)
WITH E1(N) AS (
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
), --10E+1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
-- for both a performance gain and prevention of accidental "overruns"
SELECT TOP (ISNULL(DATALENGTH(@pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
SELECT 1 UNION ALL
SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(@pString,t.N,1) = @pDelimiter
),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
SELECT s.N1,
ISNULL(NULLIF(CHARINDEX(@pDelimiter,@pString,s.N1),0)-s.N1,8000)
FROM cteStart s
)
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(@pString, l.N1, l.L1)
FROM cteLen l
;
March 21, 2012 at 5:51 pm
Lynn Pettis (3/21/2012)
Here is another way to do it:Here is the dbo.DelimitedSplit8K function:
Lynn, as we know the exact positions of the hyphen, i dont really think we would need Delimited here. it will increase the scope of work
March 21, 2012 at 7:10 pm
ColdCoffee (3/21/2012)
Lynn Pettis (3/21/2012)
Here is another way to do it:Here is the dbo.DelimitedSplit8K function:
Lynn, as we know the exact positions of the hyphen, i dont really think we would need Delimited here. it will increase the scope of work
We only think we know the position. Just because the sample data has the hyphens in the same position in each record. This is something that could change in the future. To assume it won't is to invite problems in the future.
March 21, 2012 at 7:11 pm
ColdCoffee (3/21/2012)
Lynn Pettis (3/21/2012)
Here is another way to do it:Here is the dbo.DelimitedSplit8K function:
Lynn, as we know the exact positions of the hyphen, i dont really think we would need Delimited here. it will increase the scope of work
Also, how does it increase the scope of work? The function is already written, and adding it to the select statement is easier than writing code to split the data based on something that may change.
March 21, 2012 at 7:52 pm
Lynn Pettis (3/21/2012)
We only think we know the position. Just because the sample data has the hyphens in the same position in each record. This is something that could change in the future. To assume it won't is to invite problems in the future.
OP said he is sure to have 2 dashes and he wants to grab the element between it.
Chrissy321 (3/21/2012)
Hello All,I want to extract all characters between the first and second dash.
Lynn Pettis (3/21/2012)
Also, how does it increase the scope of work? The function is already written, and adding it to the select statement is easier than writing code to split the data based on something that may change.
the scope of work SQL Server has to perform, not the dev work. And also, OP has to test the Delimited function or other any solution we might anyways, so i dont think utlizing the function will reduce the scope of dev work.
To prove my point on SQL Server's increased scope of work, i ran the delimited function code and the charindex code against a billion row table
use tempdb
go
select id = cast ( newid() as varchar(40))
into #t
from Tally
cross join ( select top 10 n from Tally ) t1
declare @i varchar(40)
set statistics io, time on
select
@i = ds.Item
from
#t t
cross apply dbo.DelimitedSplit8K(t.id, '-') ds
where
ds.ItemNumber = 2;
set statistics io, time off
set statistics io, time on
SELECT @i = LEFT ( CrsApp.CtStr , CHARINDEX('-',CrsApp.CtStr) -1 )
FROM #t t
CROSS APPLY (SELECT STUFF ( t.id , 1 , CHARINDEX('-',t.id),'') ) CrsApp (CtStr)
set statistics io, time off
and on an average here are the results:
-- delimited
SQL Server Execution Times:
CPU time = 0 ms, elapsed time = 0 ms.
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 3, logical reads 60608, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
-- charindex
SQL Server Execution Times:
CPU time = 171538 ms, elapsed time = 97528 ms.
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 1, logical reads 60608, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 14742 ms, elapsed time = 15316 ms.
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 3, logical reads 60608, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 169682 ms, elapsed time = 96775 ms.
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 1, logical reads 60608, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 14914 ms, elapsed time = 15309 ms.
After adding clustered index (which i knew wont be used)
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 3, logical reads 63706, physical reads 1, read-ahead reads 6143, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 169807 ms, elapsed time = 94632 ms.
Table '#t__________________________________________________________________________________________________________________00000000000D'. Scan count 1, logical reads 63706, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 13260 ms, elapsed time = 13435 ms.
March 21, 2012 at 8:01 pm
Thank you both.
Someone around here has something in their signature that says something like don't use code you don't understand. I don't understand the split function although I bet one day I will absolutely need it and so I am glad for the exposure to it. I also need to think about my support team and their ability to understand a solution even if I do.
I didn't understand the cross apply either but after a bit of research I do and I can explain it to my team.
I'll probably use the cross apply approach and keep the split functionality in the back of my mind.
Thanks again.
March 21, 2012 at 8:11 pm
Chrissy321 (3/21/2012)
Thank you both.Someone around here has something in their signature that says something like don't use code you don't understand. I don't understand the split function although I bet one day I will absolutely need it and so I am glad for the exposure to it. I also need to think about my support team and their ability to understand a solution even if I do.
I didn't understand the cross apply either but after a bit of research I do and I can explain it to my team.
I'll probably use the cross apply approach and keep the split functionality in the back of my mind.
Thanks again.
Read the comments in the DelimitedSplit function. Also, it has two links to articles that will help you understand how the function works.
March 21, 2012 at 8:15 pm
Will do. It's clearly well documented and thoroughly reviewed by a list of heavy hitters. Thanks again.
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