IS NULL vs equals NULL in SQL - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select rows where the column 'age' has no value.

SQL

SELECT * FROM users WHERE age [1];

Drag options to blanks, or click blank then click option'

A= NULL

BIS NOT NULL

C= 0

DIS NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' instead of 'IS NULL' causes no rows to be returned.

Confusing NULL with zero or empty string.

In SQL, to check if a column has no value (NULL), you must use IS NULL. Using = NULL does not work as expected.

2fill in blank

medium

Complete the code to select rows where the column 'email' is not missing.

SQL

SELECT * FROM contacts WHERE email [1];

Drag options to blanks, or click blank then click option'

AIS NOT NULL

B= NULL

C= ''

DIS NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' which never matches any row.

Using '= ''' which checks for empty string, not NULL.

To find rows where 'email' has a value, use IS NOT NULL. This excludes rows where 'email' is NULL.

3fill in blank

hard

Fix the error in the query to correctly find rows where 'score' is missing.

SQL

SELECT * FROM results WHERE score [1];

Drag options to blanks, or click blank then click option'

A!= NULL

B= NULL

CIS NULL

D= 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' or '!= NULL' which always return false.

Confusing NULL with zero or other values.

Using = NULL or != NULL does not work in SQL. Use IS NULL to check for missing values.

4fill in blank

hard

Fill both blanks to select rows where 'last_login' is missing and 'status' is active.

SQL

SELECT * FROM users WHERE last_login [1] AND status = [2];

Drag options to blanks, or click blank then click option'

AIS NULL

B'active'

C'inactive'

D= NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' instead of 'IS NULL'.

Forgetting quotes around string values.

Use IS NULL to check for missing 'last_login'. For 'status', use the string value 'active' to filter active users.

5fill in blank

hard

Fill all three blanks to select rows where 'comment' is not missing, 'rating' is greater than 3, and 'verified' is true.

SQL

SELECT * FROM feedback WHERE comment [1] AND rating [2] 3 AND verified = [3];

Drag options to blanks, or click blank then click option'

AIS NOT NULL

B>

CTRUE

DIS NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' or '!= NULL' for NULL checks.

Using '=' instead of '>' for rating comparison.

Using 1 or 'true' (string) instead of TRUE (boolean).

Use IS NOT NULL to find rows where 'comment' exists. Use > to check 'rating' greater than 3. Use TRUE for boolean 'verified'.