Relational Database Model: Structure, Keys, and Integrity Rules

What is a composite key?

A key composed of more than one attribute.

What is a superkey?

A key that can uniquely identify any row in the table.

What is a secondary key?

A key used strictly for data retrieval purposes without requiring a functional dependency.

What is a candidate key?

A minimal superkey that does not contain a subset of attributes that is itself a superkey.

What is a foreign key (FK)?

A primary key from one table that is placed in another table to establish a relationship.

What is the significance of the attribute domain?

It defines the specific range of values that an attribute can take.

What does it mean for a foreign key to have a null entry?

It indicates that the foreign key is not part of its table's primary key and can represent an unknown or not applicable condition.

What is the intersection of a row and column in a relational table?

It represents a single data value.

What does the primary key (PK) do in a relational table?

It uniquely identifies any given row in the table.

What is the relationship between keys and data integrity?

Keys ensure that each row is uniquely identifiable and help maintain the integrity of the data.

What is a key in a relational database?

One or more attributes that determine other attributes and ensure row uniqueness.

What is a dependent attribute in functional dependence?

The attribute whose value is determined by another attribute.

What is entity integrity?

The condition where each row in the table has a known, unique identity.

What is the primary focus of the relational database model?

The logical representation of data and its relationships.

What is the significance of the order of rows and columns in a relational table?

The order is immaterial to the Database Management System (DBMS).

What is the domain in a relational database?

The set of allowable values for an attribute.

Define functional dependence in the context of relational databases.

The value of one or more attributes determines the value of one or more other attributes.

What is the purpose of the integrity rules in a relational database?

To ensure data accuracy and consistency within the database.

What is the purpose of a data dictionary?

To provide metadata about the structure and contents of the database.

What is the role of the system catalog in a relational database?

To store metadata about the database structure and its objects.

What does the term 'tuple' refer to in a relational database?

A single row in a table that represents a single entity occurrence.

What is full functional dependence?

A situation where the entire collection of attributes in the determinant is necessary for the relationship.

What is indexing in a relational database?

A technique to improve the speed of data retrieval operations on a database table.

What is a table in the context of a relational database?

A two-dimensional structure composed of rows and columns, also called a relation.

How does the relational model handle data redundancy?

By organizing data into tables and establishing relationships to minimize duplication.

What is the requirement for primary key entries?

All primary key entries must be unique, and no part of a primary key may be null.

How does the relational model simplify database design?

By focusing on logical representation rather than physical storage details.

What does referential integrity ensure?

That a foreign key entry must have either a null entry or a matching entry in the primary key of the related table.