I am using java to make a billing program for a company. For my (poor) experience I think that the best way to keep a database active, which will be accessed and modified constantly, is using SQL. But my question arises when they have to use this program in their own PC.
To use a SQL database is it necessary to the user PC install a SQL server in their PC? (bearing in mind that they want to use the program without the need of internet). Any PC with raw Windows/Ubuntu (or any similar OS) is compatible with SQL databases? If it is not compatible which method would you use to make this kind of database?