| From: | Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> |
|---|---|
| To: | Mike Andrewjeski <Mike(dot)Andrewjeski(at)businesswire(dot)com>, "pgsql-novice(at)postgresql(dot)org" <pgsql-novice(at)postgresql(dot)org>, Kevin Grittner <kgrittn(at)ymail(dot)com> |
| Subject: | Re: convert query from mysql |
| Date: | 2013-12-17 22:08:07 |
| Message-ID: | 52B0CB47.8000507@archidevsys.co.nz |
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| Lists: | pgsql-novice |
On 18/12/13 10:55, Mike Andrewjeski wrote:
> [...]
> > 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")
[...]
Just noticed the IN clause...
The semantics of how NULLS are handled is different, but you might find
it more efficient if you don't use IN, but something like:
(SELECT n2.name FROM nodes n2 WHERE n1.name = n2.name)
I always uses aliases for tables, especially when I'm dealing with more
than one table in an SQL statement.
Cheers,
Gavin
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