IF-ELSIF-ELSE control flow in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return 'Positive' if the number is greater than zero.

PostgreSQL

SELECT CASE WHEN number [1] 0 THEN 'Positive' ELSE 'Non-positive' END AS result FROM numbers;

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

A>

B<

C=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' will check for numbers less than zero, which is incorrect here.

Using '=' will only check for numbers equal to zero.

The condition checks if the number is greater than zero to label it as 'Positive'.

2fill in blank

medium

Complete the code to return 'Negative' if the number is less than zero.

PostgreSQL

SELECT CASE WHEN number [1] 0 THEN 'Negative' ELSE 'Non-negative' END AS result FROM numbers;

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

A<

B>=

C=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' will check for numbers greater or equal to zero, which is incorrect here.

Using '=' will only check for numbers equal to zero.

The condition checks if the number is less than zero to label it as 'Negative'.

3fill in blank

hard

Fix the error in the CASE statement to handle zero correctly.

PostgreSQL

SELECT CASE WHEN number > 0 THEN 'Positive' WHEN number [1] 0 THEN 'Zero' ELSE 'Negative' END AS result FROM numbers;

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

A>

B<

C<>

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' or '<' will not correctly identify zero.

Using '<>' means 'not equal', which is incorrect here.

The condition 'number = 0' correctly checks if the number is zero.

4fill in blank

hard

Fill both blanks to complete the CASE statement that labels numbers as 'Positive', 'Zero', or 'Negative'.

PostgreSQL

SELECT CASE WHEN number [1] 0 THEN 'Positive' WHEN number [2] 0 THEN 'Zero' ELSE 'Negative' END AS result FROM numbers;

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

A>

B<

C=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for the first condition.

Using '<>' instead of '=' for the second condition.

The first condition checks if the number is greater than zero, the second checks if it equals zero.

5fill in blank

hard

Fill all three blanks to create a CASE statement that returns 'Positive', 'Zero', or 'Negative' based on the number.

PostgreSQL

SELECT CASE WHEN number [1] 0 THEN 'Positive' WHEN number [2] 0 THEN 'Zero' ELSE [3] END AS result FROM numbers;

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

A>

B=

C'Zero'

D'Negative'

Attempts:

3 left

💡 Hint

Common Mistakes

Putting 'Zero' in ELSE instead of the correct label.

Using wrong comparison operators for the conditions.

The CASE checks if number is greater than zero, equals zero, or else labels it 'Negative'.