SQLObject is an object-relational mapper, i.e., a library that will wrap your database tables in Python classes and your rows in Python instances. It currently supports MySQL through the 'MySQLdb' package, PostgreSQL through the 'psycopg' package, SQLite, Firebird, MaxDB (SAP DB), MS SQL, and Sybase. It should support Python versions back to 2.4.
SchemaCrawler is a Java API which makes working with database metadata as easy as working with ordinary Java objects. It is also a database schema discovery and comprehension and schema documentation tool. You can search for database schema objects using regular expressions, output the schema and data in a readable text format, and find potential design issues with lint . The output is designed to be diff-ed against other database schemas. SchemaCrawler supports almost any database which has a JDBC driver, but for convenience is bundled with drivers for some commonly-used RDBMS systems. SchemaCrawler works with any operating system which supports Java.
iODBC is a cross-platform Driver Manager that comforms to the Microsoft ODBC 2.x & 3.x and X/Open SQL CLI data access specs. It enables the development of database-centric solutions that are both database and platform independent. This is a great SDK for porting WIN32-based ODBC applications to Linux and other OS platforms.
DataReel is a free, cross-platform database and communications toolkit. It can be used to rapidly develop and deploy multi-threaded database and communications applications. The DataReel toolkit is composed of a modular C++ library designed to build cross-platform infrastructures for end-user applications, embedded systems, and reusable libraries. DataReel's unique modular design simplifies adaptation, allowing you to determine the level of complexity. DataReel makes Internet connectivity and database programming easy.