SQL constraints

Code pattern

Jump to a topic

See every item in the sequence

Definition

Rules on the data: PRIMARY KEY (unique identifier), FOREIGN KEY (links tables), NOT NULL and UNIQUE; in queries, constraints on results are set with WHERE.

Example: Primary key uniquely identifies each row.

Found in: syllabus, sample exam and familiarisation guidelines, school notes.

Where you'll use it in the test

Syllabus area: Y12 Programming for the Web.

Question types it can appear in

Multiple choice: Pick the option that matches the definition or example.
Fill in the blanks: Choose this term to complete a statement or table.
Short answer: Define, outline or explain it and tie it to the scenario.

Where it has appeared in the paper

The Software Engineering Project (Part A). Part letters follow each paper’s own layout.

How to use it

A model sentence

General advice, built from the definition and example above

Code pattern: “Rules on the data: PRIMARY KEY (unique identifier), FOREIGN KEY (links tables), NOT NULL and UNIQUE; in queries, constraints on results are set with WHERE.” Then apply it: Primary key uniquely identifies each row.

In a short answer, give the definition in your own words first, then tie it to the situation in the question. Do not copy the example above unless it fits the scenario.

Command words used with it

General advice

No linked question shows the command word for this term. Across the past short answer questions in this bank the words used most are: Explain, Outline, Describe, Compare, Classify, Analyse. Check the actual word in your question.

Go deeper

Flashcard: SQL constraints in Programming for the Web (Year 12) · study that set
Memorise: SQL vs ORM
Full term page: every question, note and marking comment for SQL constraints

Check yourself

Write or say the “SQL constraints” pattern from memory: the syntax and what it does.

Reveal the answer