hi, i have a table called Member_Info and its fields are

Mem_Name
Mem_Membership_ID
Mem_Status
Mem_Type
Mem_Membership_Date
Mem_Data_Of_Birth
Mem_Tel_No
Mem_Cell_No
Mem_Email
Mem_Mailing_Address

now first question is that
1). Do i make Mem_Membership_ID as primary key in this table?
2). I personally think that I add a new attribute called S.No, and that will be primary key? but the problem is that if I make S.No as primary key then there will be two attributes which can be used for primary key? so what i do now?