calling cb field values via php

Hello, I'm using cb1.7 and cbsubs. I use CB CONTENT on my site already, but would like to be able to display the CB CONTENT field conditionally, based upon the presence of another field from another table.
I'm not the best at php.
Can I insert the {cb:[cb_2]},{cb:[cb:userfield field="cb_2" /]}, or [cb_2] into a php echo? What about mysql query? It just displays the original text. Is it my syntax or an incompatibility with the substitution.

<?php
if ($num1 > 0) {
echo '{cb:[cb_2]}
';
}
?>

thoroughly confused!
fyi: i'm using jumi to inject the php into an article.

Thanks, Nat
This php works, and prints

If you've CB Content Bot (incubator project) installed you could just use substitutions to render your fields in your article directly. There would be no need for PHP. Please better clarify what you're wanting to do. CB can't render fields from non-CB databases through its API.

I am using cb content bot to display the values of a custom cb field (cb_1). However, I would like to use a php if clause to display or not display the custom cb field dependent upon the value of another variable(not a cb variable).

I see, then you should just echo your substitution if the IF statement is true. Example as follows.

No experience with your plugin that allows PHP in articles so no idea if that'll work or not. You may want to ensure that the plugin order in Joomla plugin manager has your PHP parsing plugin first so it can first determine if the substitution should be echoed in or not.