Which RDBMS best fits my need? I realise this may be come a subjective mess, but I'm hoping for some objective information on the subject. I also don't want to go shopping, I just want to know 'what to shop for'.

I'm very new to database management. As in I started SQL 4 weeks ago, and using MS Access last week. I'm coming to the end of out perrenial database project using MS Access wherein I've hit up against a lot of the limiations to Access, and I've mentioned that we need something different.

Next time round I'd like full access to the 'database capabilities' such as Union Corresponding, Intersect etc. I'd also like to be able to cursor through the rows if need be and be able to run checks row by row.

It's likely we'll have a handful of tables, but a few hundred thousand entries in the biggest table. I also need to be able to report the data. I also need to be able to import from Agresso.

One did catch my eye, which was the JPQL, in fact I could imagine the example on wikipedia fitting my needs, and I am able to code in Java. But I don't know if it fits the rest of my needs or if the project was handed over to someone not proficient in Java if it would be easily transferred. A GUI is essential.

I'm a little lost having never seen or even heard of RDBMS until last week, and now I need to decide what would work best going forward.

What RDBMS fits my needs to closest? How do I know what to pick?
My recommendation is to start out with Postgres.  The advantage is that it has a full feature set and it teaches you good habits from the start.  Once you are familiar with it, it is easier to move to up to the Oracle/DB2 approach or down to the MySQL approach easily enough.  On the other hand it is an advanced database and you can take it extremely far if you want.  And it is open source to boot.