CS-GY 6083: Principles of Database Systems
1.0.0
1.0.0
  • Introduction
  • DBMS Basics
    • Introduction to DBMS
    • Why use a DBMS instead of a File System?
    • Levels of Abstraction
    • Instances and Schemas
  • Data Models
    • Introduction to Data Models
    • Database Languages
    • Database Design
  • DBMS Internals
    • Introduction to DBMS Internals
    • Storage Manager
    • Query Processor
    • Transaction Management
    • Database Users
    • Database Architecture
  • DBMS History
  • Some Popular Database Systems
  • OLTP, OLAP, and Data Mining
  • Databases vs. Information Retrieval
  • The Entity-Relationship Model - Details
    • Introduction
    • Cardinality Constraints
    • ER Diagram Components
    • ER Diagram to Relational Schema
    • Design Issues
  • The Relational Model - Details
    • Relations
    • Keys
    • Relational Query Languages
      • Relational Algebra
      • Relational Calculus
      • Relative Expressive Power
    • Relational Operators
  • SQL
    • Introduction to SQL
    • Domain Types in SQL
    • DDL Commands
      • Creating a Table
      • Alter and Drop
    • DML Commands
      • Basic Query Structure
      • Select
      • From
      • Where
      • Joins
      • Rename
      • String Operations
      • Ordering
      • Set Operations
      • Group By and Having
      • Nested Subqueries
      • Test for Empty Relations
      • Test for Duplicate Tuples
      • Derived Relations
      • With
      • Database Modification
    • Intermediate SQL
      • Joins Revisited
      • Views
      • Transactions
      • Integrity Constraints
      • More SQL Data Types and Schemas
        • Other Features
      • Authorization
    • Advanced SQL
      • Accessing SQL From a Programming Language
        • ODBC and JDBC
        • Embedded SQL
        • PHP
        • Some Security Issues
      • Accessing Metadata
      • Text Operations
        • Like
        • Contains
      • Cursors
      • Functions and Procedures
        • Procedural Constructs
        • External Language Routines
      • Triggers
      • Ranking
      • Windowing
      • OLAP
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  1. The Relational Model - Details

Relational Operators

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Last updated 5 years ago

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There are 8 relational operators:

  1. SELECT Selects rows from a table that have specified attribute values.

  2. PROJECT Selects rows made up of a subset of columns from a table.

  3. JOIN Associates entries from two tables on the basis of matching column values.

  4. PRODUCT Builds a relation from two specified relations consisting of all possible combinations of rows, one from each of the two relations.

  5. UNION Builds a relation consisting of all rows appearing in either or both of the two relations.

  6. INTERSECT Builds a relation consisting of all rows appearing in both of the two relations.

  7. DIFFERENCE Builds a relation consisting of all rows appearing in the first and not in the second of the two relations.

  8. DIVIDE Takes two relations, one binary and one unary, and builds a relation consisting of all values of one column of the binary relation that match, in the other column, all values in the unary relation. Ex. A: B: a x x

    a y y

    a z

    b x

    c y

    => A DIVIDE B: a Basically, A/B = <m> such that for every n value in a tuple of B there is <m, n> in A.