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Relational Model Concepts:The relational Model of Data is based on the concept of a RelationThe strength of the relational approach to data management comes from the formal foundation provided by the theory of relationsRelational Model Concepts:A Relation is a mathematical concept based on the ideas of setsThe model was first proposed by Dr. E.F. Codd of IBM Research in 1970 in the following paper:"A Relational Model for Large Shared Data Banks," Communications of the ACM, June 1970The above paper caused a major revolution in the field of database management and earned Dr. Codd the coveted ACM Turing AwardInformal Definitions:Informally, a relation looks like a table of values.A relation typically contains a set of rows.The data elements in each row represent certain facts that correspond to a real-world entity or relationship In the formal model, rows are called tuples Each column has a column header that gives an indication of the meaning of the data items in that columnIn the formal model, the column header is called an attribute name (or just attribute)Informal Definitions:Key of a Relation:Each row has a value of a data item (or set of items) that uniquely identifies that row in the tableCalled the keyIn the STUDENT table, SSN is the keySometimes row-ids or sequential numbers are assigned as keys to identify the rows in a tableCalled artificial key or surrogate keyFormal Definitions:The degree of a relation is the number of attributes n of its r

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