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Conditional LEFT JOIN

Author

Topic

funk.phenomena
Posting Yak Master

121 Posts

Posted - 2012-02-15 : 10:42:51

Hi All - I have the following two tables which I am joining ...

TABLE_1

CellNumber
4165551234
4165551235
4165551236

TABLE_2

CellNumber | AREA | DATE
4165551234 01 01/05/2012
4165551234 02 12/05/2011
4165551234 03 02/05/2012
4165551235 01 01/05/2012
4165551235 02 12/05/2011
4165551235 03 02/05/2012
4165551236 10 01/05/2012
4165551236 11 12/05/2011
4165551236 12 02/05/2012

I am doing a LEFT JOIN based on the CellPhone number. In the second table, CellNumber is duplicated. I ONLY want it to join based on the MOST RECENT date for that CELLNumber. How can I achieve this with the existing code?
[CODE

SELECT T1.Cell_Number, T2.AREA FROM TABLE_1 T1
LEFT JOIN TABLE_2 T2 ON T1.CellNumber = T2.Cell_Number
[/CODE]
I would like the output as follows:

CellNumber AREA
4165551234 03
4165551235 02
4165551236 12

webfred
Master Smack Fu Yak Hacker

8781 Posts

Posted - 2012-02-15 : 10:55:07

SELECT T1.Cell_Number, T2.AREA FROM TABLE_1 T1
left join
(select row_number() over (partition by CellNumber order by [DATE] DESC)as rnum,* from TABLE_2)as t2
ON T1.CellNumber = T2.Cell_Number and t2.rnum=1

No, you're never too old to Yak'n'Roll if you're too young to die.

X002548
Not Just a Number

15586 Posts

Posted - 2012-02-15 : 11:11:32

SELECT * FROM TABLE_1 t1
WHERE EXISTS (SELECT * FROM TABLE_2 t2
WHERE t1.CellNumber = t2.CellNumber
GROUP BY CellNumber
HAVING t1.DATE = MAX(t2.DATE))

Brett

8-)

Hint: Want your questions answered fast? Follow the direction in this link
http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

Want to help yourself?

http://msdn.microsoft.com/en-us/library/ms130214.aspx

http://weblogs.sqlteam.com/brettk/

http://brettkaiser.blogspot.com/

funk.phenomena
Posting Yak Master

121 Posts

Posted - 2012-02-15 : 11:11:40

Worked like a charm, THANKS SO MUCH!

X002548
Not Just a Number

15586 Posts

Posted - 2012-02-15 : 11:54:06

Which one?

I wonder how each performs against the other

Brett

8-)

Hint: Want your questions answered fast? Follow the direction in this link
http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

Want to help yourself?

http://msdn.microsoft.com/en-us/library/ms130214.aspx

http://weblogs.sqlteam.com/brettk/

http://brettkaiser.blogspot.com/

funk.phenomena
Posting Yak Master

121 Posts

Posted - 2012-02-16 : 11:43:33

You're didn't work Brett, because t1.DATE does not exist.
DATE only exists in T2.

I appreciate you trying!

X002548
Not Just a Number

15586 Posts

Posted - 2012-02-16 : 11:49:50

my Bad..all you need is table 2 then..unless you want soemthhing else also



SELECT * FROM TABLE_2 t2a
 WHERE EXISTS (SELECT * FROM TABLE_2 t2b 
                WHERE t2a.CellNumber = t2b.CellNumber
             GROUP BY CellNumber
               HAVING t2a.DATE = MAX(t2b.DATE))

Brett

8-)

Hint: Want your questions answered fast? Follow the direction in this link
http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

Want to help yourself?

http://msdn.microsoft.com/en-us/library/ms130214.aspx

http://weblogs.sqlteam.com/brettk/

http://brettkaiser.blogspot.com/

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