20 flashcards · Shared on 19 August 2026 by AtomAI Library
Flip each card to check yourself.
What is a composite key?
A key formed from two or more fields
What is a composite key?
A key formed from two or more fields
Which description best defines a foreign key?
A field that refers to a key in another or the same table
Which situation represents a one-to-many relationship?
One customer can place several orders, while each order belongs to one customer
What does referential integrity require?
Each foreign-key value must match an existing referenced key, unless null is permitted
What does COUNT(*) return in an SQL query?
The total number of rows in the query result
A table satisfies first normal form when which condition is met?
Each field contains a single value and there are no repeating groups
Which statement describes a table in third normal form?
It is in second normal form and has no transitive dependencies involving non-key attributes
Why is GROUP BY used with aggregate functions?
To calculate aggregate results separately for categories of rows
What does an INNER JOIN return?
Rows with matching values in the joined columns of both tables
Which SQL statement retrieves selected data from a table?
SELECT
What is the role of the WHERE clause in a SELECT statement?
To specify which rows meet a condition
What is database normalisation?
Organising data to reduce unnecessary duplication and dependency problems
What dependency is removed when a table is converted from first normal form to second normal form?
A partial dependency on part of a composite key
Which SQL clause arranges query results by one or more columns?
ORDER BY
Which query returns all columns for employees whose salary is greater than 30000?
SELECT * FROM Employees WHERE salary > 30000;
Why should a DELETE statement often include a WHERE clause?
Without WHERE, all rows in the table can be deleted
What is a relational database?
A collection of data organised into related tables
Which SQL statement changes existing records in a table?
UPDATE
Which SQL statement adds a new record to a table?
INSERT
What is the purpose of a primary key?
To uniquely identify each record in a table