Click here to monitor SSC
SQLServerCentral is supported by Red Gate Software Ltd.
 
Log in  ::  Register  ::  Not logged in
 
 
 
        
Home       Members    Calendar    Who's On


Add to briefcase

Find the Nth Occurrence of a Character in a String Expand / Collapse
Author
Message
Posted Monday, September 24, 2007 1:35 AM
Valued Member

Valued MemberValued MemberValued MemberValued MemberValued MemberValued MemberValued MemberValued Member

Group: General Forum Members
Last Login: Wednesday, November 5, 2008 2:49 PM
Points: 57, Visits: 14
Comments posted to this topic are about the item Find the Nth Occurrence of a Character in a String


Post #401865
Posted Wednesday, December 2, 2009 4:55 AM
Forum Newbie

Forum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum Newbie

Group: General Forum Members
Last Login: Wednesday, December 2, 2009 4:55 AM
Points: 1, Visits: 2
helped me alot, thnx
Post #827329
Posted Wednesday, December 2, 2009 5:05 AM


SSCommitted

SSCommittedSSCommittedSSCommittedSSCommittedSSCommittedSSCommittedSSCommittedSSCommitted

Group: General Forum Members
Last Login: Friday, October 3, 2014 1:38 AM
Points: 1,678, Visits: 19,553
I suspect this would be more efficient with a numbers/tally table

declare @TargetStr varchar(8000), 
@SearchedStr varchar(8000),
@Occurrence int
set @TargetStr='a'
set @SearchedStr='abbabba'
set @Occurrence=3;

WITH Occurrences AS (
SELECT Number,
ROW_NUMBER() OVER(ORDER BY Number) AS Occurrence
FROM master.dbo.spt_values
WHERE Number BETWEEN 1 AND LEN(@SearchedStr) AND type='P'
AND SUBSTRING(@SearchedStr,Number,LEN(@TargetStr))=@TargetStr)
SELECT Number
FROM Occurrences
WHERE Occurrence=@Occurrence



____________________________________________________

How to get the best help on a forum

http://www.sqlservercentral.com/articles/Best+Practices/61537

Never approach a goat from the front, a horse from the rear, or a fool from any direction.
Post #827334
Posted Wednesday, December 1, 2010 10:22 AM
Forum Newbie

Forum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum Newbie

Group: General Forum Members
Last Login: Thursday, April 21, 2011 8:35 AM
Points: 1, Visits: 3
Looks wrong, if you go more than 1 above the maximum char number then it will loop through again.

if you change the WHILE statement from
while (@counter < @Occurrence) 

to
while (@counter &lt; @Occurrence) and @pos &lt;&gt; 0

that should fix the issue

Try running below

DECLARE @TXT varchar(255)
SET @TXT = 'Michael Williamson'
SELECT dbo.CHARINDEX2('l',@TXT,1)
SELECT dbo.CHARINDEX2('l',@TXT,2)
SELECT dbo.CHARINDEX2('l',@TXT,4)
SELECT dbo.CHARINDEX2('l',@TXT,6)

Hope that helps
Post #1028802
Posted Thursday, January 20, 2011 4:03 AM
Forum Newbie

Forum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum Newbie

Group: General Forum Members
Last Login: Thursday, January 20, 2011 4:02 AM
Points: 1, Visits: 3
Thanks! I found this function really useful. Just adding the middle line here got around the looping issue for me:

set @pos = @ret

if @pos = 0 set @counter = @Occurrence

end
Post #1050620
Posted Thursday, February 6, 2014 12:02 PM
Forum Newbie

Forum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum NewbieForum Newbie

Group: General Forum Members
Last Login: Thursday, February 6, 2014 11:42 AM
Points: 1, Visits: 1
Thank you for your fix code! I was banging my head agains the wall to find out why my stored proc was bugging out sometimes - turns out that one of my functions was using this charindex2 without accounting for looping behavior
Post #1538793
Posted Thursday, February 6, 2014 1:08 PM


Hall of Fame

Hall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of Fame

Group: General Forum Members
Last Login: Yesterday @ 6:27 PM
Points: 3,742, Visits: 8,389
This is an old thread but I would suggest a different approach. It might get give better results performance wise.
/*
Example:
SELECT dbo.CHARINDEX2('a', 'abbabba', 3)
returns the location of the third occurrence of 'a'
which is 7
*/
CREATE FUNCTION [dbo].[ProperCase]
(
@TargetStr CHAR(1),
@SearchedStr VARCHAR(8000),
@Occurrence INT = 2
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN

--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
-- enough to cover VARCHAR(8000)
WITH E1(N) AS (
SELECT N FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1))x(N)
), --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(@SearchedStr),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteAppearances(N, rn) AS( SELECT N, ROW_NUMBER() OVER (ORDER BY N) rn
FROM cteTally
WHERE SUBSTRING(@SearchedStr, N, 1) = @TargetStr
)
SELECT TOP 1 CASE WHEN rn >= @Occurrence THEN N ELSE 0 END N
FROM cteAppearances
WHERE rn = @Occurrence OR rn < @Occurrence
ORDER BY N DESC
GO

/*
Example:
SELECT dbo.CHARINDEX2('a', 'abbabba', 3)
returns the location of the third occurrence of 'a'
which is 7
*/
CREATE FUNCTION [dbo].[ProperCase2]
(
@TargetStr VARCHAR(8000),
@SearchedStr VARCHAR(8000),
@Occurrence INT = 2
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN

--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
-- enough to cover VARCHAR(8000)
WITH E1(N) AS (
SELECT N FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1))x(N)
), --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(@SearchedStr),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteAppearances(N, rn) AS( SELECT N, ROW_NUMBER() OVER (ORDER BY N) rn
FROM cteTally
WHERE SUBSTRING(@SearchedStr, N, LEN(@TargetStr)) = @TargetStr
)
SELECT TOP 1 CASE WHEN rn >= @Occurrence THEN N ELSE 0 END N
FROM cteAppearances
WHERE rn = @Occurrence OR rn < @Occurrence
ORDER BY N DESC
GO




Luis C.
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

Forum Etiquette: How to post data/code on a forum to get the best help
Post #1538817
« Prev Topic | Next Topic »

Add to briefcase

Permissions Expand / Collapse