Local/dedicated sql database for a program

Question

I have a program in C++ under development, which handles a lot of different types of objects which need to be retrieved from files on start-up. Total file size is a little less than 1GB. The program must run at least on Windows 7 and Linux.

My goal is to provide the functionality for reading from files, and storing them into objects (including data validation), so the solutions I can think of are:

1. simply provide at least one function per each object type to read from files, and copy the data to newly created objects. This is what I've been doing so far.
2. Use a database to store data and retrieve it using SQL.

I would like to switch to the second option, however I have a few limitations:

• I am not allowed to connect to the internet with my program, so a remote server database is out of the question.
• I am not allowed to make a program that forces the user to install additional software, in this case, a local database.
• Access to the local data can be done only by running the program: no additional executables that the user can run to modify or read the files.

I have searched the internet for a c++ library that allows a program to store/retrieve specific data to local files, using SQL syntax, but so far I've got nothing. Database software I know, like MySQL, Postgresql etc. won't do because of the restrictions I mentioned.

My main question is: is there such library for c++, or do I have to implement my own? I would prefer it were free, but I can do with anything I can find.

If there are no libraries like this, does anyone know any other alternatives for storing data locally for a c++ program? And if I were to implement my own, what way (as in file data structures) is there to store my objects (without it being extremely slow for less than 1GB of data)?

Answer 1

SQLite fits all your requirements except the last one, that prohibit users from modifying the data outside your program. Unfortunately, this one would be tough to overcome: a sufficiently proficient and determined user will always be able to break this restriction, even if you store your data in plain files of custom format.

Everything else fits perfectly: the database lives in a file, does not need a network connection, and can be installed as part of your program (it's a library that you link to your code).