Q:

Programming against a database in C

I want to program against various databases in C. I want to know if all of the major database providers, Oracle, DB2, Sql Server, MySql have an api to use for C. If they all do can you give me some links to what the are but more specifically, how to work with the api? 
thanks

A:

The industry standard for database connectivity is ODBC, which is a C API.  This Wikipedia link provides a brief overview and lots of links to other resources.