SQL SYNTAX TO UPDATE A RECORD IN A FIREBIRD FILE  SQL DIALECT 3

I have a FIREBIRD  data base connected by OBDC

Using VB6 i can call  customer data wich is in 2 tables located

first call    SELECT * FROM stammkunde where KUNDENNR = '         7'
will return  only the name  and phone and of customer and email in that table
and a second key     ADRKUNDID  value  to use in next call  

to make second call to other tabel  stammadresse
SELECT * FROM stammadresse  where  ADRESSID  =  ADRKUNDID



 this second table stammadresse contains

STRASSE  from   (stammadresse    street
PLZ            (from  (stammadresse    Zip
ORT           (from  (stammadresse    City
etc.

I need to update in both table the here showed fields with new data
please advise teh syntax for both SQL 's   to realize this update in VB6
Thanks