Linux group question

[kevin kempter]

Hi List;

I have 2 users which both have need to access various database related  
files.I've created a new group called 'dba'. Most of the time I want  
the users to create files with their default user:group perms, however  
when I'm working on these sql / db files I want the files to be  
created with the default user as the owner but dba as the group.

Is there a Linux command that will switch my primary group only until  
I log out of a terminal or session ?


Thanks in advance...