I have two tables: one with person information and the other with a
person's status changes/updates. (A person's status can go from
Prospective to Current to Completed.)



Code:
Person Table:
UserName FullName
jsmith Joe Smith
bjones Bob Jones
cblack Carol Black

Status Table:
UserName Status DateChanged
jsmith Prospective 1/1/2006
bjones Prospective 1/2/2006
jsmith Current 3/3/2006
cblack Prospective 3/3/2006
bjones Current 4/4/2006
bjones Completed 5/5/2006

to grab this info from these tables in a select. I'm thinking I might
need the MAX(DateChanged) in there somewhere, but I have no clue how
to use it.

Eventually my goal is to say "show me all the names of the people who
are Current".

Any ideas? Thanks in advance, I am terrible at SQL queries!

SELECT A.FullName, A.UserName, B.Status, B.DateChanged
FROM Person as A
JOIN Status as B
ON A.UserName = B.UserName
WHERE B.DateChanged =
(SELECT MAX(C.DateChanged)
FROM Status as C
WHERE A.UserName = C.UserName)

This is called a correlated subquery since it references a column from
the outer query.

Roy Harvey
Beacon Falls, CT

On Wed, 31 Oct 2007 13:08:13 -0700, melissa820 (AT) hotmail (DOT) com wrote:

melissa820 (AT) hotmail (DOT) com wrote:
I sure hope this is not homework...

Anyway, so here it goes (untested):

SELECT P.UserName
, P.FullName
, S.Status
, S.DateChanged
FROM Person P
INNER JOIN Status S
ON S.UserName = P.UserName
WHERE S.DateChanged = (
SELECT MAX(DateChanged)
FROM Status
WHERE UserName = P.UserName
)

--
Gert-Jan

(melissa820 (AT) hotmail (DOT) com) writes:
Here is a different solution from Roy's and Gert-Jan's. It only runs
on SQL 2005, but it's*potentially faster:

WITH numbered AS (
SELECT P.UserName, P.FullName, S.Status,
rowno = row_number() OVER( PARTITION BY P.UserName
ORDER BY S.DateChanged DESC)
FROM Person P
JOIN Status S ON P.UserName = S.UserName
)
SELECT UserName, FullName
FROM numbered
WHERE rowno = 1
AND Status = 'Current'


--
Erland Sommarskog, SQL Server MVP, esquel (AT) sommarskog (DOT) se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pro...ads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinf...ons/books.mspx

Thank you everyone for your help.

And no, it wasn't homework... just something I was asked to do at work
but which I'm not very familiar with.