Database for finance

Questions
1

for a wallet app, is it better to have different thing for income categories and expense categories? or just a thing of “categories” then have a category type field whether income or expense?

Also how would you structure a wallet app database for income, expense, payables and receivables?

2

You should find some websites, e-books or books on how to design a database. There are lot of materials available to learn how to create your database and understand how to use it properly.