Datasheet

SQL Server 2000 – Particulars and History

In addition to these current object models, there are a few others that you may run across and should

know about:

❑ RDO: Remote Data Objects. This was the speed leader for a couple of years. DAO and ODBC

used to be the only options for VB programmers. DAO was easier than ODBC to develop in,

but it was slow, and the object model was still too deep and complex. ODBC on the other

hand, was fast, but required tons of code just to get ready to make a connection.

RDO recognized that most of the "set-up" code for ODBC was always the same, or was predictable

based on a few other settings. It was created by using a very thing wrapper around ODBC that

substantially simplified the code while giving most of the performance benefit of ODBC.

❑ DB-Lib. Prior to version 7.0, this was the native way in which SQL Server did all of its talking

between the main host and client and utility applications (SQL Server now uses OLE DB

natively in this role). It is still actively supported, but will only be enhanced to the extent

necessary to maintain backward compatibility as SQL Server moves forward. Microsoft has

said that it will pull support for this access method at some point in the future, but it also

acknowledges that there are too many legacy applications out there using DB-Lib to figure on

dropping support for it anytime soon.

❑ VB-SQL. This was only briefly available, but still found its way into several applications. This

was based on an old wrapper that was written for VB to make many DB-Lib functions

available for VB programmers.

If you're still using VB-SQL, move off it as soon as possible. It is slow and, if it breaks, you'll

get no help with it.

❑ DAO: Data Access Objects. This is actually native to Microsoft Access (more specifically, the Jet

database that is at the heart of Access). There are a lot of applications written in VB and Access

that use this technology. Too bad! This object model can be considered clunky, slow, and just

plain outdated (believe me, I'm being nice and not saying what I really think). It's still the fastest

way to access things if you're using a Jet (Access) database but, if you're using this technology to

access SQL Server, I would suggest putting some serious effort into migrating away from it as

soon as possible. Microsoft was calling DAO a "legacy" model more than a year before the end

of the Office 97 lifecycle. They want people to stop using it, and I have to agree with them.

There are several books out there on accessing SQL Server and the data access side of the database

relationship – I'm going to leave you to look through those for more information, but I will recommend

that you check out Bill Vaughn's The Hitchhikers Guide to Visual Basic and SQL Server, Microsoft Press,

ISBN 1-572318-48-1. It is the relative bible of the connectivity side of Visual Basic programming.

Another source you may want to check out is Professional Visual Basic 6 Databases, Wrox Press, ISBN 1-

861002-02-5. C++ programmers should look at Visual C++ Database Programming Tutorial, Wrox Press,

ISBN 1-861002-41-6.