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lecture-02-intro-relational-model

lecture-02-intro-relational-model - The Relational Model T...

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The Relational Model T. M. Murali August 25, 2010 T. M. Murali August 25, 2010 CS4604: The Relational Model
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Course Outline I Weeks 1–5 , 13: Query/Manipulation Languages I The relational model I Relational Algebra I SQL I Data definition I Programming with SQL I Weeks 6–8: Data Modelling I Weeks 9–13: Relational Design I Week 14–15: Students’ choice T. M. Murali August 25, 2010 CS4604: The Relational Model
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What is a Data Model? I Data model: notation for describing data or information. T. M. Murali August 25, 2010 CS4604: The Relational Model
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What is a Data Model? I Data model: notation for describing data or information. I Structure of the data: models in databases are conceptual as opposed to physical. I Operations on the data: databases data models allow limited set of queries and modifications. I Constraints on the data: database data models support specifications of constraints on the data. T. M. Murali August 25, 2010 CS4604: The Relational Model
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What is a Data Model? I Data model: notation for describing data or information. I Structure of the data: models in databases are conceptual as opposed to physical. I Operations on the data: databases data models allow limited set of queries and modifications. I Constraints on the data: database data models support specifications of constraints on the data. I Examples of Data Models: 1. Relational data model. 2. Semi-structured data model (e.g., XML). 3. Object-relational models. T. M. Murali August 25, 2010 CS4604: The Relational Model
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The Relational Model CoursesTaken Student Course Grade Hermione Grainger Potions A- Draco Malfoy Potions B Harry Potter Potions A Ron Weasley Potions C I Structure: Table (like an array of structs) I Operations: Relational algebra (selection, projection, conditions, etc.) I Constraints: E.g., grades can be from a fixed list. T. M. Murali August 25, 2010 CS4604: The Relational Model
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T. M. Murali August 25, 2010 CS4604: The Relational Model
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The Semi-structured Model <CoursesTaken> <Student>Hermione Grainger</Student> <Course>Potions</Course> <Grade>A-</Grade> <Student>Draco Malfoy</Student> <Course>Potions</Course> <Grade>B</Grade> ... </CoursesTaken> I Structure: Trees or graphs, tags define role played by different pieces of data. I Operations: Follow paths in the implied tree from one element to another. I Constraints: Can express limitations on data types. T. M. Murali August 25, 2010 CS4604: The Relational Model
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Comparison of Models I Flexibility: T. M. Murali August 25, 2010 CS4604: The Relational Model
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Comparison of Models I Flexibility: XML models can represent graphs. T. M. Murali August 25, 2010 CS4604: The Relational Model
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Comparison of Models I Flexibility: XML models can represent graphs. I Limitations of relational model: 1. Simple, limited approach to structuring data. 2. Limited but useful set of operations on the data. T. M. Murali August 25, 2010 CS4604: The Relational Model
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Comparison of Models I Flexibility: XML models can represent graphs.
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