Return records that do not have a value in a certain field
<p>I have a Jira system that we need to do some user cleanup for. I'm blanking out on how to write this particular query. The table in question looks like this, where CHILD_ID is a username and PARENT_ID is a group name.</p>

<pre><code>CHILD_ID   |   PARENT_ID
=============================
Jane          admins
Jane          users
John          users
</code></pre>

<p>So there are multiple records per person; one for each group they belong to. I need to return a list of CHILD_ID values that <em>don't</em> have a record for the admin group - so for the example, I'd want to return John only.</p>

<p>I've tried <code>select child_id from my_table where parent_id &lt;&gt; admins</code>, but that still returns the Jane record for the users group. I know this is something I've done before, but can't seem to remember how, and can't even figure out how to word a google search for this.</p>