dbinit(), dblogin(), how often?

[Bruce.]

I'm a MS SQL newbie and am programming SQL using MS DS C++ 2003.

I'm writing sql code that will reside in a shared dll, used by many
processes and many threads in those processes.

So how often do I need to call dbinit()? Only the first time the DLL is
loaded, once per new process, once per thread, or once per database open?

Same question for dblogin().

Thanks very much for any help.
Bruce.