Untitled Flashcards Set

What does it mean that entities in the ERM correspond to a table?

Entities in the ERM correspond to a table—not to a row.

What are Relational Schemas?

The organization of a relational database as described by the database administrator.

What is a Composite Identifier in ER modeling?

A key composed of less than one attribute.

Define Simple Attribute.

An attribute that cannot be subdivided into meaningful components.

What are Single-Valued Attributes?

An attribute that can have only one value.

What are Derived Attributes?

An attribute that physically exists within the entity and is derived via an algorithm.

What do we call the entities that participate in a relationship?

Participants, and each relationship is identified by a name that describes it.

How is connectivity used in ER modeling?

To describe the relationship classification.

What is Cardinality?

A property that assigns no specific value to connectivity and expresses the range of allowed entity occurrences associated with a single occurrence of the related entity.

What does existence-dependent mean in terms of entities?

A property of an entity whose existence depends on one or more other entities.

Define existence-independent entities.

A property of an entity that can exist apart from one or more related entities.

What are Weak (Identifying) Relationships?

A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.

Define Strong (Identifying) Relationships.

A relationship that occurs when two entities are existence dependent.

What is Optional Participation in ER modeling?

A condition in which one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

What does a relationship degree indicate?

The number of attributes and participants associated with a relationship.

What is a Unary Relationship?

An ER term used to describe an association within an entity.

What is a Binary Relationship?

An ER term for an association (relationship) between two entities.

Define Ternary Relationship.

An ER term used to describe a relationship among three entities.

What are Recursive Relationships?

A relationship found within a single entity type.

What does the ER Model use associative entity represent?

An M:N relationship between two or more entities.

Describe the process of database design.

It is typically not linear; but rather iterative or sequential.

What is the role of design standards in database design?

To conform to standards that minimize data redundancies and reduce data anomalies.

What is the significance of processing speed in database design?

It is essential for organizations that generate large numbers of transactions.

What do column aliases do in SQL?

Allow you to assign a temporary name to a column or expression within a query result set.

What are Computed columns in SQL?

Expressions that calculate values dynamically based on other columns or constants in the query.

What does the DISTINCT keyword do in SQL?

It returns unique values from a column or a combination of columns, eliminating duplicates.

Define a NATURAL JOIN.

A type of join that combines tables based on columns with the same name and compatible data types.

What is the purpose of the JOIN USING syntax in SQL?

To specify the exact column(s) to join on, particularly when the column names are the same.

What does the JOIN ON syntax specify?

The exact column(s) to join on, particularly when the column names in both tables are the same.