Which base is best?

Question

Database

I’m making a small program in c#, so it needs a database where, for example, 500,000 users will be stored (phone number login password fio currency), and you need to find users in it, for example, by phone and so that it’s straight fast, enter the number and you have already displayed the user .
Which one is suitable for this?

Answer 1

The base is small. Any will do. Let's say postgresql. Just do not forget the index on the field with the phone