One possible way to do this is to setup a roles table in your database that associates X role to a user logon and then execute a query specific query based upon the role the user is in.
Something like this would suffice
string role = "";
//execute scalar and assign the value to role
//Execute HR Query
//Execute Payroll Query
Alternatively you could combine the scalar step and the switch statement into a single stored procedure but I think it is overkill for what you are trying to do.
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