CASE WHEN expression in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the grade based on score using CASE WHEN.

MySQL

SELECT score, CASE WHEN score >= 90 THEN 'A' ELSE 'F' END AS grade FROM exams WHERE score [1] 80;

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

A!=

B<

C=

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '>=' causes only scores exactly 80 to be selected.

Using '<' selects scores less than 80, which is opposite of the goal.

The condition >= checks if the score is at least 80 to filter the rows.

2fill in blank

medium

Complete the code to assign 'Pass' or 'Fail' based on marks using CASE WHEN.

MySQL

SELECT student_id, marks, CASE WHEN marks [1] 50 THEN 'Pass' ELSE 'Fail' END AS result FROM results;

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

A>=

B<

C=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' assigns 'Pass' to marks below 50, which is incorrect.

Using '=' only passes marks exactly 50, missing others.

The operator >= checks if marks are 50 or more to assign 'Pass'.

3fill in blank

hard

Fix the error in the CASE WHEN expression to categorize age groups.

MySQL

SELECT name, age, CASE WHEN age [1] 18 THEN 'Minor' ELSE 'Adult' END AS age_group FROM people;

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

A<

B=>

C<=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=>' causes syntax error.

Using '==' is not valid in SQL for comparisons.

The correct operator to check if age is 18 or less is <=. The option => is invalid syntax in SQL.

4fill in blank

hard

Fill both blanks to classify salary levels using CASE WHEN.

MySQL

SELECT employee_id, salary, CASE WHEN salary [1] 50000 THEN 'Low' WHEN salary [2] 100000 THEN 'High' ELSE 'Medium' END AS salary_level FROM employees;

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

A<

B>=

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' in the first blank would misclassify salaries equal to 50000.

Using '<' in the second blank would misclassify salaries exactly 100000.

The first condition checks if salary is less than 50000 for 'Low'. The second checks if salary is 100000 or more for 'High'. Salaries in between are 'Medium'.

5fill in blank

hard

Fill all three blanks to create a CASE WHEN expression that labels product stock status.

MySQL

SELECT product_name, stock, CASE WHEN stock [1] 0 THEN 'Out of stock' WHEN stock [2] 50 THEN 'Low stock' ELSE 'In stock' END AS stock_status FROM inventory WHERE stock [3] 0;

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

A=

B<=

C>

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '<=' in second blank excludes stock exactly 50.

Using '!=' instead of '=' in first blank misclassifies zero stock.

Using '<' instead of '>=' in third blank excludes zero stock.

The first blank checks if stock equals 0 for 'Out of stock'. The second checks if stock is 50 or less for 'Low stock'. The WHERE clause filters products with stock greater than or equal to 0.