AHIC Review Course 6: Relational and Nonrelational Database Designs

Flashcards covering relational model basics, constraints, keys, SQL usage, and the NoSQL landscape, including the four NoSQL types and their use cases.

What data model stores data in individual tables (relations) that can be linked to other tables to enrich information?

The relational model.

Who first described the relational model and in what year?

EF Codd, 1969.

In a relational database, what is a relation?

A table (relation) that contains rows (records) and columns (attributes); each row is unique.

What is a record (or tuple) in a relation?

A single row representing a unique instance of data.

What is an attribute in a relation?

A column with a specified data type that stores a particular kind of data.

What is a primary key?

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

What is a foreign key?

An attribute in one relation that references the primary key of another relation, enabling table relationships.

True or false: In the relational model, relations have an inherent order of rows.

False — rows have no inherent order; they can be sorted by a user but are not stored in a specific order.

How are multivalued attributes handled in the relational model?

They are not stored in a single cell; multiple values are modeled with multiple records (one-to-many design).

What does NULL represent in a relational database?

The absence of data; NULL means no value and is not equal to another NULL.

What is the closed world assumption in relational databases?

If there is no record stating a fact, the fact is assumed not true (nonexistence implies nonexistence).

What are the two main types of keys discussed that relate tables in a relational database?

Primary keys (unique row identifiers) and foreign keys (references to primary keys in other tables).

What can SQL be used to do in a relational model?

Query, transform, and reconstruct data by joining relations to answer questions.

What is NoSQL?

A nonrelational database paradigm with looser data models, designed for big data and distributed storage.

Name the four NoSQL database types discussed.

Key-value store, column store, document store, and graph database.

What is a document store particularly good at?

Storing a wide variety of data points about a single thing in documents (e.g., JSON or XML); efficient for many attributes about one entity, but harder to join across documents.

What is a graph database best at?

Storing data nodes and edges to emphasize relationships and connections between data points.

Which NoSQL type would be most appropriate to store a huge set of pathology reports?

Document store.