How can I only display results where a field is in a table returned by another query

[jacu86]

I have data in two different applications. I need to get fields from one query to use as filters for another, like this:

app=app1 | rex field=environment_url "https:\/\/(?<app_name>.*)\.foo\.com" | where app_name in [ search app=app2  | table app_name ]

app2 has a field named app_name which I'm turning into a table. app1 doesn't have this field, but I'm creating and extracting it with a regex. 

I only want the app names from app1 if they exist in the table I'm creating from app2. This query isn't working for me, what can I do? Thank you for any help.

[richgalloway]

The where command does not support the IN operator (which must be in upper case, BTW).  You can use the in function with where or the IN operator with search.  However, since the IN operator is converted to a series of ORs under the covers and the subsearch will return a series of ORs, I recommend not using IN.

app=app1 | rex field=environment_url "https:\/\/(?<app_name>.*)\.foo\.com" | search [ search app=app2  | table app_name | format ]