Relational Database Concepts Flashcards

Which three are true about the CREATE TABLE command?

Answer: It can include the CREATE...INDEX statement for creating an index to enforce the primary key constraint

When creating a table in Oracle SQL, you can define a primary key constraint, which implicitly creates a unique index to enforce its uniqueness and non-nullability. This index is essential for efficient data retrieval and maintaining data integrity. Therefore, the `CREATE TABLE` command can indeed include statements that lead to the creation of an index for the primary key constraint.

Which of the following best describes a relational database?

Answer: A database that organizes data into tables, with rows and columns, where each table represents an entity.

A relational database organizes data into structured tables, where each table represents an entity and consists of rows (records) and columns (attributes). These tables are related to each other through common fields, allowing for efficient storage, retrieval, and management of interconnected data. This tabular structure with defined relationships is the defining characteristic of a relational database.

What is the primary key in a relational database table?

Answer: A column or set of columns that uniquely identifies each row in the table.

The primary key in a relational database table is a crucial constraint that uniquely identifies each individual row within that table. It ensures that every record is distinct and provides a reliable way to reference specific data. This uniqueness is fundamental for data integrity and establishing relationships with other tables.

What is a foreign key in a relational database?

Answer: A key that is used to link two tables together by establishing a relationship.

A foreign key is a column or set of columns in one table that refers to the primary key in another table. Its primary purpose is to establish and enforce a link or relationship between two tables. This ensures referential integrity, meaning that relationships between data are consistent and valid across the database.

Which of the following is true about relational databases?

Answer: They use tables to store data, where each table consists of rows and columns.

Relational databases are fundamentally structured around tables, which are composed of rows and columns. Each row represents a single record, and each column represents an attribute of that record. This tabular structure is central to how relational databases store, organize, and manage data, allowing for clear definition and relationships between data entities.