Hi,
 
You need to simulate logging in with multiple users. It would be handy if you have multiple PC's that are part of the same LAN network.
 
What you would do is to put the database on a shared drive so both PC's can access it. This would be the case for MS Access for example. When you use Oracle or SQL Server or MySQL, e.g. you would not need to do this. You then need to ensure the database is "visible" from outside of the PC. For example with Oracle you would need to start a listener service. What you need to do is specific for each database type.
 
Then the testing is rather simpel. Just start SQL*XL on both PC's and connect to the same database.
 
Interesting scenario's to test are read consitency tests where you for example update on one PC the same data you are retrieving on the second PC. Before you commit the updated changes the other database users should see the old data when read consistency is supported in the database.
 
Hope this helps,
 
Gerrit-Jan Linker