subselect syntax - Mailing list pgsql-novice

From Steve Lefevre
Subject subselect syntax
Date
Msg-id 46672978.2000909@osu.edu
Whole thread Raw
Responses Re: subselect syntax  ("Phillip Smith" <phillip.smith@weatherbeeta.com.au>)
Re: subselect syntax  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: subselect syntax  (Michael Glaesemann <grzm@seespotcode.net>)
List pgsql-novice
Hello everyone -

I'm moving from MySQL to Postgres and I am in a situation where I am
trying to use subselects properly.

I have a table of projects, users, and user_projects. The table
user_projects creates a many-to-many relationship between users and
projects.

I'm creating a select list on a web form for adding a new user to a
project. I want to select users from the user table, who aren't
already listed in the join table under that project.

Here's my select:
SELECT * FROM users
WHERE user_id <> $current_user_id
AND user_id <> ( SELECT user_id FROM user_projects WHERE project_id =
$project_id )

This query returns no rows, even on projects that have no records in
the user_projects table!

I am certain that I am not the $current_user_id. If I run this query:
SELECT * FROM users
WHERE user_id <> $current_user_id

I get all the user records besides myself.

What am I doing wrong?

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