Database per application VS One big database for all applications [closed]

Neither way looks ideal

I think you should consider not making references in database layer for cross-application relations, and make them in application layer. That would allow you to split it to one database per app.

I'm working on one app with 100+ tables. I have them in one database, and are separated by prefixes - each table has prefix for module it belongs to. Then i have built a layer on top of database functions to use this custom groups. I'm also building data administrator, which takes advantage of this table groups and makes editing data very easy.

It depends and your options are a bit different depending on the database and frameworks you're using. I'd recommend using some sort of ORM and that way you don't need to bother that much. Anyways you could probably put each app in it's own schema in the database and then either reference the shared tables by schemaname.tablename or create views in each application schema that's just a SELECT * FROM schemaname.tablename and then code against that view.

There are no hard and fast rules to choose one over the other.

Multiple databases provide modularity. As far as sync-ing across multiple databases are concerned, one can use the concept of linked servers and views thereof and can gain the advantages of integrated database (unified access) as well.

Also, keeping multiple databases can help better management of security, data, backup & restore, replication, scaling out etc!

My 2cents.