Relational Database Design Concepts
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Relational Database Design Concepts

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Questions and Answers

Define the term 'relation' in the context of the relational data model mentioned in the text.

A named two-dimensional table of data.

What is a 'primary key' in the context of a relation in a database?

An attribute or a combination of attributes that uniquely identifies each row in a relation.

Explain the concept of a 'composite key' in the context of a database relation.

A primary key that consists of more than one attribute.

What is the role of a 'foreign key' in a relation within a database?

<p>It is an attribute in a relation that serves as the primary key of another relation in the same database.</p> Signup and view all the answers

What are the properties of relations in a database according to the text?

<ol> <li>Each relation has a unique name. 2. Each entry is atomic. 3. Each row is unique. 4. Each attribute has a unique name. 5. The sequence of columns is insignificant. 6. The sequence of rows is insignificant.</li> </ol> Signup and view all the answers

Study Notes

Relations and Keys in a Database

Relations

  • A relation represents a table in a relational database, consisting of rows (tuples) and columns (attributes).

Primary Key

  • A primary key is a column or set of columns in a relation that uniquely identifies each row (tuple) in the table.

Composite Key

  • A composite key is a primary key composed of more than one column, where the combination of values is unique for each row.

Foreign Key

  • A foreign key is a field in a relation that refers to the primary key of another relation, establishing a relationship between the two tables.

Properties of Relations

  • Relations in a database have the following properties:
    • Each row is unique
    • Each column has a unique name
    • All rows have the same number of columns
    • The order of columns is significant
    • The order of rows is insignificant

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Description

Learn about key concepts and principles of designing a relational database, including relations, primary keys, composite keys, and foreign keys. This lecture covers logical database design and the relational data model.

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