Patrick, THANKS!
Chip On Wed, 30 Oct 2019 11:08:35 -0700 (MST), Patrick Emanuel via 4D_Tech wrote: > <quote author='4D Tech mailing list'> > Hi, > I understand that if a component needs to have access to 1 or more > tables there are 2 ways to do this: > - Inject the table definition(s) into the host > - USE DATABASE and connect to an external database/datafile. > > I have some questions about using external databases in the context of > a component. > > Given the following situation: > [Host_Database] <- [component] -> [external_for_Component] > > - in the case of client/server how is the external database managed? > -- would I place it in the component's resource folder? > -- is it automagically moved to the client via some other mechanism? > -- or is the component's external database call passed back to the > server, call(s) made and then data transferred to client from server? > -- something else > > - As I read the 4D docs it seems that the external database can NOT > have/use a field of type C_Object as this is not supported by SQL, and > access is done to the external database only through SQL. > -- Is this a correct interpretation? > > - In a component with an external database, would I need to switch back > and forth between access to the external database and the host system? > ex: > method call from host includes pointer to table or field of host. To > satisfy the method call, data from the external database needs to be > accessed. I USE DATABASE(External) to the external database do query, > get data. > - do I need to place the retrieved external database data into > variable(s)? > - do I need to then USE DATABASE(Host) before working with the host > table/field(s)? > > Thanks for answering, and any other tips you may have regarding > external databases and components. > > Chip > We have done so much, with so little, for so long; > We are now qualified to anything with nothing <sigh> > - unknown > ********************************************************************** > 4D Internet Users Group (4D iNUG) > Archive: http://lists.4d.com/archives.html > Options: https://lists.4d.com/mailman/options/4d_tech > Unsub: mailto:4d_tech-unsubscr...@lists.4d.com > ********************************************************************** > </quote> > > Hi Chip, > > I use this mecanism every time in QS Toolbox and will speak about > this during the presentation planned next January. > You really pointed out how to manage. Now, about C_OBJECT, I don't > save them. One trick could be to Jsonify it as text and perform the > reverse action when you need to get access to the information. > > So, I manage action on server with the option 'Execute on server' as > method's property and for variable, I use GET/SET VARIABLE TO > VARIABLE commands. > > Here is a SQL code on how to manage action executed on external > database and internal one: > Begin SQL > USE REMOTE DATABASE DATAFILE :[$QS_VCS_COMP_DB_PATH] AUTO_CLOSE; > > SELECT count(*) > from VCS > INTO :[$Count]; > > USE DATABASE SQL_INTERNAL; > > End SQL > > You can ping me directly at: pat.emanuel67 @ gmail. com > > Patrick > > > _____________________________________ > Sent from http://4d.1045681.n5.nabble.com > > ********************************************************************** > 4D Internet Users Group (4D iNUG) > Archive: http://lists.4d.com/archives.html > Options: https://lists.4d.com/mailman/options/4d_tech > Unsub: mailto:4d_tech-unsubscr...@lists.4d.com > ********************************************************************** We have done so much, with so little, for so long; We are now qualified to anything with nothing <sigh> - unknown ********************************************************************** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **********************************************************************
