Which one of the following attribute can be taken as a primary key?

Quiz on the concept of Relational Model. These include relational and database schema, keys and relational query operators. The relational model (RM) is a logical model for database design that uses a structure and language consistent with first-order predicate logic. The RM was developed by Edgar F. Codd, an English computer scientist, in the 1970s. The RM represents data as tuples, or groups of related data values in a row, that are grouped into relations. The RM also separates logical data structures, such as data tables, views, and indexes, from physical storage structures. This... Show more

Quiz on the concept of Relational Model. These include relational and database schema, keys and relational query operators.

The relational model (RM) is a logical model for database design that uses a structure and language consistent with first-order predicate logic. The RM was developed by Edgar F. Codd, an English computer scientist, in the 1970s. The RM represents data as tuples, or groups of related data values in a row, that are grouped into relations. The RM also separates logical data structures, such as data tables, views, and indexes, from physical storage structures. This separation allows database administrators to manage physical data storage without affecting access to that data as a logical structure. 

The RM is based on n-ary relations, which is a normal form for database relations. The RM can be translated from the ER model, which maps entities and relationships of the conceptual ER schema into relations and integrity constraints of the logical RM schema. 
The relational model describes data as named relations of labeled values. For example, customer IDs can relate with customer names and addresses as Customer: {<(CustomerID, 11111), (Name, Pat), (Address, 12 Maple)>, <(CustomerID, 22222), (Name, Tracy), (Address, 44 Elm)>}. 

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