NOT NULL and DEFAULT constraints in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a column that cannot have NULL values.

MySQL

CREATE TABLE users (id INT, name VARCHAR(100) [1]);

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APRIMARY KEY

BNOT NULL

CAUTO_INCREMENT

DDEFAULT 'anonymous'

Attempts:

3 left

💡 Hint

Common Mistakes

Using DEFAULT instead of NOT NULL

Forgetting to add any constraint

The NOT NULL constraint ensures the column cannot have NULL values.

2fill in blank

medium

Complete the code to set a default value for the column 'status'.

MySQL

CREATE TABLE orders (order_id INT, status VARCHAR(20) [1]);

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ANOT NULL

BPRIMARY KEY

CDEFAULT 'pending'

DUNIQUE

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOT NULL instead of DEFAULT

Forgetting to quote string default values

The DEFAULT constraint sets a default value when no value is provided.

3fill in blank

hard

Fix the error in the column definition to correctly set NOT NULL and DEFAULT constraints.

MySQL

CREATE TABLE products (id INT, price DECIMAL(5,2) [1] DEFAULT 0.00);

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ANULL

BAUTO_INCREMENT

CPRIMARY KEY

DNOT NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using NULL instead of NOT NULL

Omitting NOT NULL when DEFAULT is present

The NOT NULL constraint must be explicitly stated to prevent NULLs even if a DEFAULT is set.

4fill in blank

hard

Fill both blanks to create a column 'age' that cannot be NULL and has a default value of 18.

MySQL

CREATE TABLE members (id INT, age INT [1] [2] 18);

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ANOT NULL

BDEFAULT

CAUTO_INCREMENT

DUNIQUE

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of NOT NULL and DEFAULT

Using AUTO_INCREMENT instead of DEFAULT

Use NOT NULL to prevent NULLs and DEFAULT 18 to set the default age.

5fill in blank

hard

Fill all three blanks to create a table with a 'username' column that is NOT NULL, UNIQUE, and has a default value 'guest'.

MySQL

CREATE TABLE accounts (id INT PRIMARY KEY, username VARCHAR(50) [1] [2] [3] 'guest');

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ANOT NULL

BDEFAULT

CUNIQUE

DAUTO_INCREMENT

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up UNIQUE and NOT NULL

Placing DEFAULT before NOT NULL

Using AUTO_INCREMENT incorrectly

The username column must be NOT NULL, UNIQUE, and have a DEFAULT 'guest' value.