iodbc.ads is a free binding for Ada to the free iODBC driver manager that can
be used to access all Data Bases with has an ODBC call interface.
iodbc_w32.ads is the same file but with the C convention replaced with
Stdcall convention for use with Windows 95/Windows NT instead of the existing
odbc2.ads/odbc2.adb is a thick binding to odbc inspired by Pascal Obry's
binding. I have used a similar version using odbc from the win32ada binding
for two years with a minimum of problems at my work.
iODBC Web Page