DatabasesLesson 1 of 3 in the course Relational model and SQL

Relational Database Foundations: Queries, Integrity, SQL, and Dependencies

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

The relational model provides a systematic way to represent and query data. It treats information as values arranged in tuples and grouped into relations, while drawing on ideas from logic.

The relational model (RM) is an approach to managing data in which data is represented by tuples grouped into relations. A database organized this way is a relational database. English computer scientist Edgar F. Codd first described the model in 1969 and published its influential formulation in 1970.

All flashcards

What is the relational model?
A data model that represents data as tuples grouped into relations.
What is a declarative query?
A request that specifies the desired result while leaving the DBMS to choose how to retrieve it.
Who first described the relational model?
Edgar F. Codd, who described it in 1969 and published an influential formulation in 1970.
How can a tuple be interpreted logically?
As a proposition or fact that is treated as true when the tuple occurs in its relation.
What does the Information Principle require?
All database information is represented by attribute values in tuples within relations identified by relvars.

Quiz questions

  1. In relational algebra, which operation keeps selected attributes while removing other attributes?Answer: Projection
  2. In a relational database, what condition does a foreign key enforce?Answer: Its values correspond to key values in the referenced relation.
  3. Which statement describes a difference between SQL tables and mathematical relations?Answer: SQL may allow duplicate rows, while a mathematical relation is a set.
  4. What does a functional dependency X→YX \rightarrow Y state?Answer: Matching values for XX require matching values for YY.
  5. What is a central aim of database normalization?Answer: Reducing modification anomalies in relation designs.

Based on the Wikipedia article Relational model, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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