convert query from mysql

Hi all,

psql newbie here. I'm working to convert a mysql query written in ruby to using postgres as our database is now postgres 9.2

Here's the mysql query:

select nodes.name, GROUP_CONCAT(node_groups.name) from node_groups,
node_group_memberships, nodes where nodes.id =
node_group_memberships.node_id and node_groups.id =
node_group_memberships.node_group_id and nodes.name IN (SELECT name
from nodes) group by nodes.name order by nodes.name")
What I'm having an issue with is the IN Clause. Not sure how to do that in psql.

This is what I've got so far any comments are more than welcome:

select nodes.name, node_groups.name from node_groups, node_group_memberships, nodes where nodes.id=node_group_memberships.node_id and node_groups.id=node_group_memberships.node_group_id ;

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