I was thinking about creating a personalized chess database for my correspondence chess play. What sorts of contents are useful to put in it and is there any big difference in having your own database versus just using one from online. The main factor that contributed me to do this was to deepen my opening knowledge of certain openings. I am open to any other reasons why I should or shouldn't create one.
For correspondence I keep a database of my personal opening book that I extend whenever I encounter a new move. I include notes on things like why I chose a particular line and both numeric and verbal position assessment. I also include select text from books or other databases that discuss that position.
The question is why only one database?
I have a database of my own games, and a second for casual games I find interesting. You could have one for your OTB games, and correspondence games, for example.
Beyond that, you could have a database of both your white and black repertoire. This is very common among higher-rated players.
Lastly, if you are really into openings like an IM friend of mine, who has written about 10 books, you could have a database for every opening you want to study in-depth. This is a good thing to keep separate since it just makes it easier to manage.
I currently have in excess of 10 personal databases that I have created in ChessBase, and MANY more if you include other databases I have that are purchased.