querying vs using relationship list and iterate

[Nishant Neeraj]

Hi,

I have three tables USERS, MEMBERSHIPS, GROUPS -- where membership is a
linking table that joins users and groups in many-to-many relationship, and
also stores users' role in the group.

Sometime when I need to know whether a user exists in a group [or what role
a user has in a group], I can do it by two ways:

1. groups.getMembershipList() and iterate over the list inflating each
member and comparing with the User object that is on test. like

for(Membership m: g.getMembershipList())
{
   if(m.getUser().equals(testUser)
       return true;
}

Or.

2. I can just write a query using Expression.

Expression.forString(Membership.class, "user = $testUser and group=$group");


Can someone suggest which one is better approach? Or, is there a even better
third approach?

Thanks
Nishant