This is entirely straightforward if you know how to write VBA code, but not
otherwise.

1) The contents of the form field are each identifable by bookmark, as shown
in the form field properties dialog.

2) In VBA you write an SQL statement using the form field values, open the
database and execute the SQL statement.

3) You associate the log/submit button with the macro that does all this.

Do a Google on VBA code samples: what you're asking is a very common
requirement.

You can use ADO (ActiveX Data Object) to connect to your DB, using the
SQL Provider (driver), such as

'Prompt for username and password
oConn.Properties("Prompt") = adPromptAlways
oConn.Open "Driver={SQL Server};Server=Aron1;DataBase=pubs;"

(If you've done any ASP work...it's very similar.)

You'll then need to either open a table to add a new record or run a
query to find the RS to update. Then capture and pass the info from
the form fields into the DB and update.

You'll find an article on this process, along with a downloadable
sample for Access (which will be more or less the same except for
using the SQL provider versus the Jet one for Access).  The code is
open so you can mess with the code, DB and form to see how it works.
You'll find this here:

Word AutoForm Articles
http://www.mousetrax.com/techpage.html#autoforms

Specifically...look for the Please Fill Out This Form series...article
# 5 w/download.

You may also want to check out this book...great for getting you up to
speed, quickly. http://www.mousetrax.com/books.html#ado.

Good luck...

Dian D. Chapman, Technical Consultant
Microsoft MVP, MOS Certified
Editor/TechTrax Ezine

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