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Relational Databases

Relational Databases. Relational Algebra (2) Set operators, renaming, notation. Relational Algebra (2). Relational algebra query (expression) on set of relations produces relation as a result College ( cName , state , enrollment ) Student ( sID , sName , GPA , sizeHS )

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Relational Databases

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  1. Relational Databases Relational Algebra (2) Set operators, renaming, notation

  2. Relational Algebra (2) Relational algebra query (expression) on set of relations produces relation as a result College(cName,state,enrollment) Student(sID,sName,GPA,sizeHS) Apply(sID,cName,major,decision) College Student Apply

  3. Relational Algebra (2) Union operator List of college and student names College Student Apply

  4. Relational Algebra (2) Difference operator IDs of students who didn’t apply anywhere IDs and names of students who didn’t apply anywhere College Student Apply

  5. Relational Algebra (2) Intersection operator Names that are both a college name and a student name College Student Apply

  6. Relational Algebra (2) Intersection doesn’t add expressive power (1) College Student Apply

  7. Relational Algebra (2) Intersection doesn’t add expressive power (2) College Student Apply

  8. Relational Algebra (2) Rename operator 1. 2. 3. College Student Apply

  9. Relational Algebra (2) Rename operator To unify schemas for set operators List of college and student names College Student Apply

  10. Relational Algebra (2) Rename operator For disambiguation in “self-joins” Pairs of colleges in same state College Student Apply

  11. Relational Algebra (2) Alternate notation (1) Assignment statements – Pairs of colleges in same state College Student Apply

  12. Relational Algebra (2) Alternate notation (2) Expression tree – GPAs of students applying to CS in CA College Student Apply

  13. Relational Algebra (2) Relational Algebra summary

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