: Among Oracle and SQL server, which would you think is more suitable for an online application?..in terms of multiple user who could be accessing the database at the same time.
You can't go wrong with either one. They are both heavy-duty "mission critical" servers.
Depending on what day it is, either Oracle or SQL will have some features that the other doesn't Usually that changes with the next release.
I'd take a look at the features for both, and make sure that one or the other isn't missing something important to you.
That said, I've always use SQL server, either Microsoft's, or the earlier Sybase versions. I've never used Oracle. SQL has always had what I needed, and it's what I started with. I tend to stay with what I know, unless there's a compelling reason to change.
There has been no compelling reason for me to change to Oracle. Just as there's been no compelling need to change to SQL Server 2000. I'm still running 6.5 and 7.0 in my installations.
Let us know what you decide, and why. It's always interesting to see what people do...