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Chapter 4 Relational Algebra

Chapter 4 Relational Algebra. Relational Languages Relational Algebra. Relational Languages. Procedural language Relational algebra Non-procedural language Relational Calculus (pp.101- 107). Relational Algebra Intra Relation. Selection - horizontal partition

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Chapter 4 Relational Algebra

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  1. Chapter 4Relational Algebra • Relational Languages • Relational Algebra

  2. Relational Languages • Procedural language • Relational algebra • Non-procedural language • Relational Calculus (pp.101- 107)

  3. Relational AlgebraIntra Relation • Selection - horizontal partition • SELECT relation WHERE condition [GIVING relation] • condition(relation) • Projection - vertical partition • PROJECT relation OVER (attribute, attribute,...)[GIVING relation] • attributes(relation)

  4. Union-Compatible • Union - tuples in either of 2 union compatible relations • relation1 UNION relation2 [GIVING relation] • relation1  relation2 • Difference - tuples in one union compatible relation, but not other • relation1 MINUS relation2 [GIVING relation] • relation1 - relation2

  5. Union-Compatible • Intersection - tuples in both of 2 union compatible relations • relation1 INTERSECT relation2 [GIVING relation] • relation1  relation2

  6. Any 2 Relations • Product - Cartesian product of any two relations • relation1 TIMES relation2 [GIVING relation] • relation1 relation2 • Join - common domain • relation1 JOIN relation2 WHERE condition [GIVING relation] • relation1conditionrelation2 • Division • relation1 divided by relation2 [GIVING relation] • relation1 / relation2

  7. Types of Join • Equi : based on equality with 2 identical attribute columns • Theta : a join based on a relational operator (=,<,>,<=,>=,~=) • Natural : equijoin with no duplicate column • Outer : includes tuples without matches (left, right, full)

  8. Types of Join • Semi-join • relation1 SEMIJOIN relation2 WHERE condition [GIVING relation] • relation1 lxcondition relation2 • Semi-theta-join • Semi-natural join

  9. Assignment • Review chapters 1-4 • Read Chapters 6-5 • Do Exercise 4.12 • Due date:

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