All quizzesEasy

Keys, Types & Constraints

Preview — 3 of 10 questions

What is a surrogate key in a relational database?

AA natural key derived from the business domain

BA system-generated key with no business meaning (e.g., auto-increment integer or UUID)

CA composite key made up of multiple columns

DA key shared between two related tables

What does a FOREIGN KEY constraint enforce in a relational database?

javascript

CREATE TABLE orders (
  id          SERIAL PRIMARY KEY,
  customer_id INT NOT NULL REFERENCES customers(id)
);

AIt ensures the column values are unique across the table

BIt ensures that a value in one table corresponds to an existing value in another table (referential integrity)

CIt prevents NULL values in the referenced column

DIt automatically creates an index on the referenced column

How is a one-to-many relationship typically implemented in a relational database?

javascript

CREATE TABLE customers (id SERIAL PRIMARY KEY, name TEXT NOT NULL);
CREATE TABLE orders (
  id          SERIAL PRIMARY KEY,
  customer_id INT NOT NULL REFERENCES customers(id),
  total       NUMERIC(10,2)
);

ABy adding a foreign key column in the child table referencing the parent table's primary key

BBy creating a junction table between the two entities

CBy adding a column in the parent table referencing the child table's primary key

DBy duplicating rows in both tables

Answer all 10 questions (7 more), see explanations for every answer, and track your score.