Re: [SQL] locked my keys in the car - Mailing list pgsql-sql

Thomas Good wrote:

> Hello again...
>
> The original post in this thread was - - -
>
> > > What I would like to do is this:
> > > SELECT id, MAX(date)
> > > FROM table
> > > WHERE office='M'
> > > AND case='A' OR case='I';
>
> This because, my original (badly formed) query:
> SELECT id, date
> FROM table
> WHERE office='M'
> AND case='A' OR case='I';
> was returning 48,552 rows...abit more data than I needed...
>
> Thanks to Dave Madden, James Boorn, & Federico Passaro, I reduced this
> output to 12,978 rows:
>
> SELECT id, MAX(date)
> FROM table
> WHERE office='M'
> AND case='A' OR case='I'
> GROUP BY id;
> But this was still problematic, as the rows are patients and
> 12,978 patients (in a 15 bed ward) is a bit of overcrowding!
> (Although we could use the revenue... ;-)
>
> Next I tried Richard Lynch's suggestion:
> SELECT id FROM table
> WHERE office = 'M' AND (case = 'A' OR case = 'I')
> ORDER BY date DESC;
>
> And this is definitely on the right track as I am now down to
> 75 patients (thanks Rich).
>
> The 13 active cases (in what we loosely term reality) are amongst
> the 75 returned tuples.  Moreover, I can catch the 62 inactive cases
> listed amongst the output from Rich's query with:
>
> SELECT tr_id, tr_date FROM crtrd1
> WHERE tr_unit = 'SMA' AND (tr_type = 'T' OR tr_type = 'O')
> ORDER BY tr_date DESC;
>
> (In this instance, T=terminated and O=outgoing...)
>
> So my next question is:
> Is there a way, using SQL, to do the math on this, i.e., to rm the
> patients who appear twice - once in the first query, once in the second?
> (God forbid we re-admit the same patient at some future date!)
>
> In other words, can I somehow go about rm'ing those patients who have
> a tr_type of T or O - with a tr_date that is > the tr_date of the entry
> with a tr_type of I or A?
>
> We are getting into Byzantine complexities here, SQL wise, and I am
> tempted to just dump the output to a (perl) filehandle and let perl
> sort the data - but I am curious if SQL can hack it...
>
> Thanks alot,
> Tom
>
>     ---------- Sisters of Charity Medical Center ----------
>                    Department of Psychiatry
>                             ----
>     Thomas Good                          <tomg@q8.nrnet.org>
>     Coordinator, North Richmond C.M.H.C. Information Systems
>     75 Vanderbilt Ave, Quarters 8        Phone: 718-354-5528
>     Staten Island, NY   10304            Fax:   718-354-5056

Hi Thomas

this should be another step toward the solution of your sql problem (I
hope!)

SELECT C1.tr_id, C2.tr_date FROM crtrd1 C1, OUTER  crtrd1 C2
WHERE C1.tr_unit = 'SMA' AND (C1.tr_type = 'T' OR C1.tr_type = 'O') AND
C2.tr_unit = 'SMA' AND (C2.tr_type = 'I' OR C2.tr_type = 'A') AND
C1.tr_id = C2.tr_id AND
C1.tr_date > C2.tr_date
ORDER BY tr_date DESC;

Cheers

federico