| Re: IDL/Dataminer/mySQL is working!! [message #26385 is a reply to message #26384] |
Mon, 03 September 2001 00:34  |
Olaf Stetzer
Messages: 39
Registered: September 2001
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Member |
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Olaf Stetzer schrieb:
>
> For those of you who want to give this combination a try
> some hints:
>
> You have to install the myODBC-driver on the machine where
> you run IDL. I had problems with the recent version 2.50.38
> however the older version 2.50.37 is working for me.
> The maintainers of myODBC are aware of the problem, maybe
> there will be a workaround or bugfix in one of the next versions.
Update: There now is a bugfix available!!! The bug was confirmed
by the developers after I sent them a log of myODBC. Now there
is a bugfix introduced in the binary-packages (still ending .38).
I _love_ open source software!!! :-)
Someone asked me to show a bit of code I used to connect to
the database, so here it is (very dirty, maybe I convert it to
a nice reusable function soon):
-----------------------------------------
pro database_test
oDB = obj_new('IDLDBDatabase')
oDB->Connect, DataSource = 'PSC6', user='aida', password=''
strSQL='SELECT Zeitpunkt, Pabs, Tgk FROM aida_me�daten WHERE Zeitpunkt
BETWEEN "2001-07-06 14:45:00" AND "2001-07-06 15:05:00";'
oRS = obj_new('IDLDBRecordset',oDB,SQL=strSQL)
status = oRS->MoveCursor(/FIRST)
zeitfirst=oRS->GetField(0)
Zeit=replicate(zeitfirst,900)
Pabs=DBlarr(900)
Tgk=dblarr(900)
for i=0,899 do begin
IF(status NE 1) THEN BEGIN
PRINT, 'Error moving database cursor'
RETURN
ENDIF
Zeit(i)=oRS->GetField(0)
Pabs(i)=oRS->GetField(1)
Tgk(i)=oRS->GetField(2)
status = oRS->MoveCursor(/NEXT)
endfor
plot, Tgk, Pabs
OBJ_DESTROY, oRS
OBJ_DESTROY, oDB
end
------------------------------------------------
So the Dataminer are mainly the two objects IDLDBDatabase and
IDLDBRecordset. The first is used to establish a connection
via ODBC, the second is used to access the data either of a complete
table within the DB or to a subset which is returned after submitting
a SQL-query (like I did in my example).
I still have to think of an elegant way to convert the struct
SQL-Timestamp
into a variable which ca be used to be plotted against....
Greetings,
Olaf
--
Dr. Olaf Stetzer
Forschungszentrum Karlsruhe
Institut f�r Meterologie und Klimaforschung
Atmosph�rische Aerosole (IMK III) - http://imk-aida.fzk.de
Tel.: +49(0)7247-82-3249 (FAX: -4332)
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