Re: insufficient key column information

bangorme_at_hotmail.com (Scott) wrote

> I'm not sure that that's the type of problem I'm having. In theory, I
> should be able to plug any supported db into an application using ADO,
> and it should work.

Correct. But in practise things unfortunately works a bit differently.

I used to be a big supported of developing database vendor independant clients. Not any more. The cost of developing the front-end client fades into insignificance when compared to the investment a company makes in its server platforms and database software.

You want a client that exploits that and provides a return on that investment made. Besides, a company is not likely to run Sybase today, Oracle tomorrow and Informix next week. If anything, the database environment is one of the few things that do remain consistant for longish periods in most companies.

Add to that databases can be *very* different from one another. Oracle is unlike SQL-Server in many cases. What works in SQL-Server, will cause major problems in Oracle, and vice versa.

> never expected the problems I've had. For example, duplicates are
> easily handled by Access and SQL Server 7 because the recordset brings
> table relationships into the recordset.

ADO is designed for MS-Access and SQL-Server primarily. If anything, you're always ensured of smooth integration when dealing with Microsoft only software.

> > Back in '94 I did my own port of a VB app I did, from MS Access, to
> > SQL-Server 4. Performance sucked (and a single app instance loaded,
> > generated 50% of the total LAN traffic).
> >
>
> Did you ever discover where the loss in performance came from?

Data controls. I stay away from data controls as far as possible. You can not trust a data control to generate the correct SQL for all situations. Instead, I rather write my own classes and provide data bounding with them. Delphi though makes it a lot easier as you have a TUpdateSQL class which you can use to override the update, insert and delete SQLs that a data bound control will generate.

> I'm about to start from scratch (I would have it done by now)

If anything Scott, it will be a good learning experience IMO. The important thing is to know how Oracle works. Transaction-wise, multi-versioning wise and so on. I strongly recommend Tom Kyte's book called 'Oracle: Expert one-on-one'. It is written for the developer in clear and concise languge showing you the strenghts of Oracle and what pitfalls to avoid.

--
Billy