Re: convert query from mysql - Mailing list pgsql-novice

From Gavin Flower
Subject Re: convert query from mysql
Date
Msg-id 52B0CB47.8000507@archidevsys.co.nz
Whole thread Raw
In response to Re: convert query from mysql  ("Mike Andrewjeski" <Mike.Andrewjeski@businesswire.com>)
Responses Re: convert query from mysql  (Gavin Flower <GavinFlower@archidevsys.co.nz>)
List 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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