Wolfgang,
What you need is the Microsoft ODBC 2.0 Programmer's Reference and SDK Guide.
I just checked and there are a couple available on ebay for less than $10.
QEDBF04.DLL and QEOR504.DLL are odbc drivers.I suspect they are ODBC version 2
or 2.5. The drivers implement the functions
described in chapter 22. There are 56 functions listed in the chapter, but those
two drivers probably don't implement all 56 functions. I have attached the help
file for Q+E "flat file" drivers, which include the dBase driver. That help lists
the ODBC functions the driver supports. (I could only find **08.DLL version drivers
right now.)
You can, in theory, call the ODBC functions directly in the driver without going
through ODBC.DLL - which is what DBExpert is apparently doing. What ODBC.DLL does
is load the driver and its functions, do some error checking on function calls,
maybe allocate some memory, call the function in the driver and return the values.
DBExpert is apparently doing that.
So you could build a "forwarder", named QEDBF04.DLL (or QEOR704.DLL) which would forward
the functions called by DBExpert to ODBC.DLL. Alternately you could forward the functions
directly to your target database, but then you would have to write something specific
for each database you wanted to target. Which is exactly what ODBC is designed to get around.
You could also build your forwarder to forward directly into another ODBC driver. The issue
with doing that is you would have to handle the differences between OBDC versions and do
that for each ODBC driver - once again something that ODBC.DLL does for you. For example
the ODBC driver I could find for mySQL is ODBC version 3, and some of the ODBC function
names changed from version 2 to version 3, along with some of the parameters.
I have attached the ODBC SDK from Devcon vol 9 disk 2. [modified text and attachment to replace the copy I originally attached, which I had altered (the first attachment) to compile against odbc v 2 and v 3]