Subject Re: Data module with a complex index From Robbie Nott <robnott@mweb.co.za> Date Fri, 6 Dec 2019 22:36:09 +0200 Newsgroups dbase.getting-started Hi Mervyn Eskom is a disgrace ! Bought a 1000 Watt inverter at the Chinese flea market ( R500 ) When the power goes off I attach it to my car battery and my PC runs fine. Not sure how long it'll last - have used it for 4 hours and the car started just fine. As for the Data module I'm battling with, please see my reply to Akshat Am wanting to do the 2 key relationship in the data module and not sure how to implement in the data module. Many thanks :-) On 06/12/2019 11:52, Mervyn Bick wrote: > On 06/12/2019 11:39, Robbie Nott wrote: > >> Hi Mervyn >> Thanks for the reply >> dBase 12 >> Attempting to learn the data modules. >> >> 3 tables, Show, cat and ring >> Many cats per show, many rings per cat >> >> Show table has the ShowNo field. >> Cat table has ShowNo and CatNo fields. >> Ring table has ShowNo and Catno fields which are the >>   fields used to filter the Ring records >> >> Rings don't have a unique number, rather they are linked >> by show and cat number. >> Existing system creates a concatenated key of >> Show["ShowNo"] + Cat["CatNo"] for restricting the ring records. >> Ring table has a ShowCat index, and program uses a setRange(). >> >> Wanting to do a data module for this and not sure how to proceed. >> Perhaps a calculated virtual field in the Cat table ? > > I'm afraid this has to be very short.  The power is due to go off in 15 > minutes.  (It was off last night from 20:00 and although it was due to > come back on at 23:00 it only came back on at about 07:00 this morning.) > > A datamodule is just a container for queries.  This makes it easy to use > the same query in different forms and reports without having to craft > (or copy) the same SQL statement over and over. > > You can place exactly the same query you used before in the datamodule. > When you drag the datamodule onto a form instead of referring to the > query as form.queryname you refer to it as form.datamodulename.queryname > > When (if :-) ) the power comes back on I'll add to this. > > Mervyn. > > > >