Need help with duplicate query

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Need help with duplicate query

Author

Topic

pjyelton
Starting Member

4 Posts

Posted - 2010-03-19 : 19:38:53

Hello, I need help with writing a query. Basically what I want to do is give a unique identifier for each group of duplicates in a table. For example, if this is my data:


FIRST   LAST    AGE  DUPENUM
BOB     JONES   16
BOB     JONES   16
BOB     JONES   34
TOM     ADAMS   21
JOE     BROWN   37
TOM     ADAMS   21
JOE     BROWN   37

and I want my duplicate to be FIRST/LAST/AGE, after the query is run the table looks like this:


FIRST   LAST    AGE  DUPENUM
BOB     JONES   16   1
BOB     JONES   16   1
BOB     JONES   34
TOM     ADAMS   21   2
JOE     BROWN   37   3
TOM     ADAMS   21   2
JOE     BROWN   37   3

So each new duplicate group gets the next available dupenum.

Thanks for any help!

khtan
In (Som, Ni, Yak)

17689 Posts

Posted - 2010-03-19 : 20:10:32

what is the version of SQL Server you are using ?

KH
[spoiler]Time is always against us[/spoiler]

pjyelton
Starting Member

4 Posts

Posted - 2010-03-19 : 23:47:02

2005, although in the end this code will instead be run as a stored procedure through Java.

khtan
In (Som, Ni, Yak)

17689 Posts

Posted - 2010-03-20 : 00:04:07

[code]
DECLARE @sample TABLE
(
[FIRST] varchar(10),
[LAST] varchar(10),
[AGE] int
)
INSERT INTO @sample
SELECT 'BOB', 'JONES', 16 UNION ALL
SELECT 'BOB', 'JONES', 16 UNION ALL
SELECT 'BOB', 'JONES', 34 UNION ALL
SELECT 'TOM', 'ADAMS', 21 UNION ALL
SELECT 'JOE', 'BROWN', 37 UNION ALL
SELECT 'TOM', 'ADAMS', 21 UNION ALL
SELECT 'JOE', 'BROWN', 37

SELECT s.[FIRST], s.[LAST], s.AGE, d.[DUPENUM]
FROM @sample s
LEFT JOIN
(
SELECT [FIRST], [LAST], AGE,
[DUPENUM] = dense_rank() OVER (ORDER BY [FIRST], [LAST], AGE)
FROM @sample
GROUP BY [FIRST], [LAST], AGE
HAVING COUNT(*) > 1
) d ON s.[FIRST] = d.[FIRST]
AND s.[LAST] = d.[LAST]
AND s.[AGE] = d.[AGE]

/*
FIRST LAST AGE DUPENUM
---------- ---------- ----------- --------------------
BOB JONES 16 1
BOB JONES 16 1
BOB JONES 34 NULL
TOM ADAMS 21 3
JOE BROWN 37 2
TOM ADAMS 21 3
JOE BROWN 37 2

(7 row(s) affected)
*/
[/code]

KH
[spoiler]Time is always against us[/spoiler]

pjyelton
Starting Member

4 Posts

Posted - 2010-03-20 : 00:17:21

Brilliant, thanks!!!

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