Re: New Era good for Real Time responses?

In article <816450656.11574@arcfan.demon.co.uk> alex@arcfan.demon.co.uk (Alex McLintock) writes: >From: alex@arcfan.demon.co.uk (Alex McLintock) >Subject: New Era good for Real Time responses? >Date: Wed, 15 Nov 1995 23:50:53 GMT >Hypothetical situation: >We have factories with large databases controlling stock, machines, etc etc. >The users need good GUI's to access these centralised tables. >However some equipment might change those tables at any time. >Can I get the GUI programs to respond to a change in the table? >I know this is very sketchy - but we are talking hypothetically. >I assume that the central database has some kind of triggers and >that the network is functional. >In the office we are discussing the relative merits of New Era, >Delphi, etc etc without any hard facts or experience. Makes discussion a lot easier! Ian >Thanks >Alex >alexmc@biccdc.co.uk It's a good while since I played about with something like this but I linked an old version of the VisionWare tool SQLRetriever (that's the present name, I can't remember if the older version had a different name) to Excel using DDE. There was a mechanism in there to repeat the select at intervals although I can't remember whether it was in DDE itself or in the VisionWare product. There was certainly a means of forcing the client to update the display if the data changed as part of DDE. As far as I can see getting the select to be re-run periodically is the only way of doing this. There's no magic way of connecting the whole table in parallel, as it were, to some mechanism to detect a change in some particular row. The nearest you might get would be to arrange for the updating process to broadcast a message to clients in some way to tell them a change had been made and that they should reselect. Ian