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Unformatted text preview: Relation schema <=> Type in programming language Relation <=> Variable in programming language Relation instance <=> Value of the variable Properties of relations The tuples in a relation instance are not ordered. There are no duplicate tuples The attributes in a relation are distinct. There are no duplicate attribute names in a relation schema All attributes are atomic Relation schema <=> a set of attributes Relational data integrity Referential integrity foreign keys ensure that the rows referenced exist (no unmatched values). Entity integrity primary key attributes cannot take NULL values. Relational data manipulation Relational algebra Relational calculus o Domain calculus o Tuple calculus Relational algebra and relational calculus are equally powerful. Anything done with one can be done with the other. Database...
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