uSQLite is a network wrapper for SQLite. It turns SQLite into an RDBMS but puts the emphasis on the 'Lite'. In fact it works in a somewhat unconventional mmanner in order to make both servers and clients as light, portable and simple as possible. Readers who are not familiar with SQLite are advised to visit www.sqlite.org.
c-dax is a C library for accessing SQL databases using a uniform programming interface. It's designed as a lightweight wrapper, with both static binding and dynamic library API. Supports SQLite 3, PostgreSQL 8.3, and MySQL 5. Check out c-dax if you want
NWrapper was built to be a quick wrapper for storing and executing multiple NMap commands (using SQLite), but it can do a lot more. Also, it was a way for me to start learning C (hence the lack of data structures or anything fancy).
CDB is a abstract and simple wrapper to different client libraries of sql databases. It is written in C and C++. Supported are PostgreSQL, MySQL, SQLite and Oracle rdbms. It should run in many modern Linux and BSD environments.