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SQL QUERY most recent date for a person_id returning all rows

Posted on 2004-09-16
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Last Modified: 2008-01-09
Hi Guys
I've tried for days to figure this problem out
Any help would be great.

I want the query to retrieve the most recent for each person_id along with all information contained within the row.

EXAMPLE TABLE
auto_id  person_id   grade_id   grade_date
1          1           1         12/12/2003
2          2           1         12/06/2003
3          2           2         12/07/2003
4          1           2         12/01/2004
5          1           3         24/03/2004

THE RESULTS SET I WANT IS:-
auto_id  person_id   grade_id   grade_date
3          2           2         12/07/2003
5          1           3         24/03/2004

I HAVE TRIED QUERIES

SELECT person_id, MAX(grade_date)
FROM grade_history
GROUP BY person_id
//But that only gives me two columns i need the whole row

SELECT person_id, grade_id, grade_date
FROM grade_history
WHERE grade_date=(SELECT MAX(grade_date)
              FROM grade_history);

//But that only gives me one result set of the most recent date NOT the most recent date for a person_id

IF you could shed any light on this problem it would be most welcome.


Chad
0
Comment
Question by:Chad_MacArthur
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8 Comments
 
LVL 15

Expert Comment

by:jdlambert1
ID: 12080234
Try this. If you're using Oracle prior to 9i, or another SQL flavor that doesn't support ANSI-standard JOIN syntax, let us know and we'll give you the older structure.

SELECT gh.*
FROM grade_history gh
INNER JOIN (
 SELECT person_id, MAX(grade_date) as grade_date
 FROM grade_history
 GROUP BY person_id
) maxdate m ON gh.grade_date = m.grade_date AND gh.person_id = m.person_id
0
 
LVL 15

Accepted Solution

by:
jdlambert1 earned 500 total points
ID: 12080265
Fixing a cut/paste error:

SELECT gh.*
FROM grade_history gh
INNER JOIN (
 SELECT person_id, MAX(grade_date) as grade_date
 FROM grade_history
 GROUP BY person_id
) m ON gh.grade_date = m.grade_date AND gh.person_id = m.person_id


And the non-ANSI syntax:

SELECT gh.*
FROM grade_history gh,
( SELECT person_id, MAX(grade_date) as grade_date
 FROM grade_history
 GROUP BY person_id
) m
WHERE gh.grade_date = m.grade_date AND gh.person_id = m.person_id
0
 
LVL 2

Expert Comment

by:montasirma
ID: 12080320
Try the following
SELECT person_id, MAX(grade_id), MAX(grade_data) FROM grade_history
GROUP BY person_id DESC;
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LVL 15

Expert Comment

by:jdlambert1
ID: 12080354
montasirma, it may vary with the version of SQL, but on most systems your query structure will return the highest grade_id and grade_date independent of each other for each person_id. Chad appears to need the most recent grade_id for each person_id, and if so, he needs to correlate the person_id and maximum grade_date with the main table.
0
 
LVL 1

Expert Comment

by:sachinrp
ID: 12141214
Hi ,

This simple query will give you desired result set

SELECT * from example
where person_id||grade_date in (select person_id||MAX(grade_date)
FROM example
GROUP BY person_id)
order by grade_date


Sachin
0
 
LVL 1

Expert Comment

by:sachinrp
ID: 12141217
replace example table with grade_history
0

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