Keys Let KcR K is a superkey of R if values for K are sufficient to identify a unique tuple of each possible relation r(R) by"possible r"we mean a relation r that could exist in the enterprise we are modeling. Example:{customer_name,customer_street}and {customer_name} are both superkeys of Customer,if no two customers can possibly have the same name In real life,an attribute such as customer id would be used instead of customer name to uniquely identify customers,but we omit it to keep our examples small,and instead assume customer names are unique. Database System Concepts-5th Edition,Oct 5,2006 2.12 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 2.12 ©Silberschatz, Korth and Sudarshan th Edition, Oct 5, 2006 Keys Let K  R K is a superkey of R if values for K are sufficient to identify a unique tuple of each possible relation r(R) by “possible r ” we mean a relation r that could exist in the enterprise we are modeling. Example: {customer_name, customer_street} and {customer_name} are both superkeys of Customer, if no two customers can possibly have the same name  In real life, an attribute such as customer_id would be used instead of customer_name to uniquely identify customers, but we omit it to keep our examples small, and instead assume customer names are unique