Ambiguous reference to field ca

I want to delete this post

You should create index

CREATE INDEX join_reachEffect_user ON default('User|' || TOSTRING(`user`)) USING GSI

and change your query to

SELECT count(*) 
  FROM reachEffect u 
  LEFT OUTER JOIN reachEffect ca ON KEY ('User|' || TOSTRING(ca.`user`)) FOR u 
 WHERE u._type = 'User' 
   AND (ca._type = 'Campaign' OR ca._type IS missing)

is this you want?

I know I can do this I have done this but I need like above can I do it ??