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Unformatted text preview: join to get a new relation, which we call Student Exam , which merges the two relations on their common attribute: name address number grade . . . . . . . . . . . . Brown, B 5 Lawn Rd. 105 A Smith, J 9 Elm St. 156 A Walker, S 4 Ash Gr. 189 C . . . . . . . . . . . . Notice that candidate 167 did not sit the exam, and so therefore does not appear in the join. We can deFne this join operation quite easily using our logical notation: Student Exam (n,a,no,g) Student (n,a,no) Exam (no,g) In the language of database theory, it is usually given a more readable form, such as join Student and Exam over number 22...
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This note was uploaded on 01/02/2010 for the course MATH Math2009 taught by Professor Koskesh during the Spring '09 term at SUNY Empire State.
- Spring '09