Adagio core modules are written in Delphi. GridView and the Financial Reporter are written in Visual C. System components are written in C++. Adagio has its own database manager built in. Adagio ODBC allows external applications to read (and write if you're very careful) data to the Adagio files.

SQL is a database access language, not an application development language.

What prompts the question? It's not typically asked by people in the accounting department!