working with two tables under one function

hi guys,am new to code igniter though am learning quickly.my issue is am trying to get data from from two tables lets say after a user registers they are taken to login which is fine my issue is.when a new user ligs in they are redirected to a page to fill in their profile but when they come back to the site and they filled their profile i want them redirected to their respective profiles.

when trying to get data from the two tables its working but when the profile table doesnt contain the foreign key it displays a page yes but with the data array error.since the array is empty.
my code below
                     

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