The relational algebra provides the theoretical underpinnings for data retrieval from a relational database. Due to its well-defined semantics, relational algebra expressions can be extensively optimized, which is critical so that queries can be executed efficiently.

Learning Objectives

  • Describe the purpose of the following relational operators
    • selection (\(\sigma\))
    • projection (\(\pi\))
    • rename (\(\rho\))
  • Manipulate relational data using the aforementioned operators

How to Complete this Lesson

Complete the following learning activities: (1.25–1.5 hours total)

  1. Read “Data Retrieval From a Relational Database” in Fundamentals of Database Management Systems Chapter 5: The Relational Database Model: Introduction (15–30 minutes)
  2. Attend the class meeting (60 minutes)

Resources

Relational algebra (Wikipedia)

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