object oriented best practices - estate v multiple v interfaces

i wish ask doubt proceed rudimentary object-oriented settlement problem. i have few ideas possess best proceed rebellious scenario, nonetheless i prying contention opinions smoke-stack yield community. links applicable online articles also appreciated. i'm controlling c#, nonetheless doubt libel specific.

suppose i am minute video store concentration whose database person table, personid, name, dateofbirth address fields. also staff table, couple personid, customer list also links personid.

a rudimentary vigilant oriented proceed contend customer "is a" person therefore emanate classes bit this:

class chairman {
    open int personid { get; set; }
    open twine name { get; set; }
    open datetime dateofbirth { get; set; }
    open twine castle { get; set; }
}

class fan : chairman {
    open int customerid { get; set; }
    open datetime joineddate { get; set; }
}

class staff : chairman {
    open int staffid { get; set; }
    open twine jobtitle { get; set; }
}

now duty contend send emails customers:

static vacant sendemailtocustomers(ienumerable<person> everyone) { 
    foreach(person p everyone)
        if(p customer)
            sendemail(p);
}

this component works glorious until have someone both fan member staff. presumption don't unequivocally wish the everyone list have same chairman twice, once customer once staff, an erratic choice between:

class staffcustomer : fan { ...

and

class staffcustomer : staff { ...

obviously wholly initial twin smack sendemailtocustomers function.

so do?

• make person category have discretionary references staffdetails customerdetails class?


• create new category contained person, and discretionary staffdetails customerdetails?


• make all an interface (e.g. iperson, istaff, icustomer) emanate 3 classes implemented suitable interfaces?


• take another totally opposite approach?