Help with SQL query?

[melissa820@hotmail.com]

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

>From the Status Table it's obvious that "bjones" is Completed,

"cblack" is Prospective, and "jsmith" is Current. But I'm not sure how
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!

[Gert-Jan Strik]

Re: Help with SQL query?

melissa820@hotm ail.com wrote:

>
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
>

From the Status Table it's obvious that "bjones" is Completed,

"cblack" is Prospective, and "jsmith" is Current. But I'm not sure how
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!

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

[Roy Harvey (SQL Server MVP)]

Re: Help with SQL query?

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.DateChang ed)
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@hotm ail.com wrote:

>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
>

>>From the Status Table it's obvious that "bjones" is Completed,

>"cblack" is Prospective, and "jsmith" is Current. But I'm not sure how
>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!

[melissa820@hotmail.com]

Re: Help with SQL query?

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. :)