How to check if a record is existing in a custom table.

[Indira8]

Hi All, 

We have a custom table where there are 3 reference fields dep, owner and escalation which refer to the user table. 
Requirement is that whenever logged in user tries to access the catalog item , if user is a part of any of these then certain variables should be visible otherwise no.
Could you help me with the code for querying the custom table and checking if the logged in user record is present in any of the fields.

Thank you 

[Ankur Bawiskar]

@Indira 

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Regards
Ankur