Upload Presentations Using Slideshare Application                 Jennifer Widom
The Relational Model Used by all major commercial database systems Very simple model Query with high-level languages: s...
The Relational ModelDatabase = structuralfor “unknown” relations in databaseKey – attribute of named relations (or tables)...
The Relational ModelCreating relations (tables) in SQLCreate Table Student(ID, name, GPA, photo)Create Table College  (nam...
The Relational Model Used by all major commercial database systems Very simple model Query with high-level languages: s...
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  1. 1. Upload Presentations Using Slideshare Application Jennifer Widom
  2. 2. The Relational Model Used by all major commercial database systems Very simple model Query with high-level languages: simple yet expressive Efficient implementations Jennifer Widom
  3. 3. The Relational ModelDatabase = structuralfor “unknown” relations in databaseKey – attribute of named relations (or tables) Schema set whose value is unique “undefined”NULL – – structural description of orin each databaseSchemaspecial value description of relations intupleEach relation has a contents at given point inarecolumns)Or set of attributes whose combined values (orInstance –= actual set of named attributes timeunique Instance actual contents at given point in timeEach tuple (or row) has a value for each attributeEach attribute has a type (or domain) Jennifer Widom
  4. 4. The Relational ModelCreating relations (tables) in SQLCreate Table Student(ID, name, GPA, photo)Create Table College (name string, state char(2), enrollment integer) Jennifer Widom
  5. 5. The Relational Model Used by all major commercial database systems Very simple model Query with high-level languages: simple yet expressive Efficient implementations Jennifer Widom

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