ITM531CS524 Object Oriented Modeling and Design

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ITM531/CS524Object Oriented Modeling and Design

• Module 2
• Relational Model

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Graphic representation
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Example for relational model
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Relational query language

• Algebraic approach.
• Functional approach.

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Algebraic approach

• Relational Algebra Operators
• UNION (Rel-1, Rel-2)
• INTERSECT (Rel-1, Rel-2)
• DEFFERENCE (Rel-1, Rel-2)
• TIMES(Rel-1, Rel-2)
• SELECTION (Rel, Bool-Exp)
• PROJECTION (Rel, Select-List)
• JOIN (Rel-1, Rel-2)

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Graphic representation
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Select relation

• Predicate (table-name)
• Example Query the database to get all the
  department information with more than 1M budget.
  - Budget gt 1M (Department)
• Results
• DEPT CHAIRMAN BUDGET
• CS Smith 1.5M
• EE York 2M

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Projection relation

• Col-name col-name (table-name)
• Example Query the database to get all the
  student name. Name (Student)
• Results
• Name
• Jim
• Sue
• Bob

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Equijoin

• Table-name 1 ? table-name-2
• Example Get all the student information and the
  department information for all students in the
  database. Student ? Department.
• Results
• STUID NAME DEPT CHAIRMAN BUDGET
• 003 Bob Bio Dillion 1M
• 001 Jim CS Smith 1.5M
• 002 Sue EE York 2M