table variables

Are there table variables in postgresql that you can include in a join?
If there are other suggestions as to how I can get done what I need
done, I would appreciate those as well.

What I am trying to do is write a multi step query, where it would be
much much much more efficient to create a temp table, so a single insert
and then populate it with update statements.
The problem is that you can't use a temp table in functions without
dynamic execute statements, and those don't work for other parts of the
code (besides the fact that they're confusing).

I was thinking a table variable, such as exists in msssql, would be the
perfect answer.

What I'll probably end up doing is having a permanent table and
including the ip address of the client machine, so that each time it is
used the data can be easily deleted.