In a physical database model, how are table relationships represented?

In a physical relational database model, relationships between tables are implemented and enforced using foreign keys. A foreign key is a column or a set of columns in one table that refers to the primary key of another table. This creates a link between the two tables, ensuring referential integrity, which means that a value in the foreign key column must match an existing value in the referenced primary key column. This mechanism is the standard way to represent one-to-one, one-to-many, and many-to-many relationships at the physical implementation level.

A. Data types define the kind of data a column can hold (e.g., number, text), not the relationship between tables.
B. Primary keys uniquely identify records within a single table; they are the target of a relationship, not the representation of it.
C. Table names are identifiers for tables and do not inherently define or represent the relationships that exist between them.

1. Oracle Corporation. (2023). Oracle Database Concepts

23c. Chapter 2

"Data Blocks

Extents

and Segments

" Section: "Overview of Schema Objects". It describes how constraints

including foreign keys

are schema objects that define relationships.

2. Oracle Corporation. (2023). Oracle Database SQL Language Reference

23c. Chapter 8

"Constraints

" Section: "Foreign Key Constraints". This section explicitly states

"Foreign keys represent relationships between tables."

3. Silberschatz

A.

Korth

H. F.

& Sudarshan

S. (2019). Database System Concepts (7th ed.). McGraw-Hill. Chapter 3

"Introduction to SQL

" Section 3.7

"Complex Integrity Constraints in SQL

" discusses how foreign key declarations specify relationships between tables.