ch4

Join Operation

A database operation that takes two relations and returns a result relation where tuples match under a specified condition.

Cartesian Product

An operation that pairs each tuple from one relation with every tuple of another relation.

Natural Join

A join operation that combines tuples from two relations based on matching attribute values.

Outer Join

An extension of the join operation that includes unmatched tuples from one or both relations, filling in with nulls.

View

A virtual relation in SQL created by a query expression, which can hide certain data from users.

Integrity Constraints

Rules that ensure data in the database remains accurate and consistent, protecting against accidental damage.

Primary Key

A unique identifier for a record in a relation that cannot accept null values.

Foreign Key

An attribute that creates a link between two relations, ensuring that a value in one relation matches a value in another.

SQL Data Types

Categories of data that determine the kind of value a column can hold, such as INTEGER, VARCHAR, or DATE.

Authorization

Permissions granted to users allowing them to perform certain tasks on database objects.

Transaction

A sequence of operations performed as a single logical unit of work that is either fully completed or rolled back.

Materialized View

A database object containing the results of a query that is stored on disk for performance optimization.

Tuple

A single row in a relation, representing a record of related data.

Subquery

A query nested inside another SQL query, used to provide results to the enclosing query.

Data Consistency

The state of a database where all data is accurate, valid, and maintained according to integrity constraints.

SQL Schema

A blueprint or structure that defines the organization of data in a database, including tables and their relationships.