and I know that SQLConfigDataSource is listed in odbccp32.lib, and I have that in my list of Additional Dependencies under Linker input for the project. But despite all attempts with many different settings, etc, I cannot get past:
error LNK2019: unresolved external symbol _SQLCONFIGDATASOURCE
Fortran is case-insensitive whereas C is case-sensitive (and there are other differences). You will have to provide a proper interface for this and other routines from that library, along the lines of ISO_C_BINDING (the module and the keywords).