You can set the INCLUDE environment variable to point to the directory that contains the DB-Library SQLFRONT.H and SQLDB.H include files. Alternatively, you can use the /I compile line switch to point to the include file directory.
Since your application must always include the WINDOWS.H, SQLFRONT.H, and SQLDB.H files, you don't need to define the DB-Library functions you use. These functions and their proper declarations are already defined in the include file.
You must define an application's target operating system before including the DB-Library header files. Use the following statements at the beginning of all SQL Server applications that will run with the Windows operating system:
#define DBMSWIN
#include <windows.h>
#include <sqlfront.h>
#include <sqldb.h>