LOOP, WHILE, FOR iterations in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a LOOP in PostgreSQL procedural language?

A LOOP is a control structure that repeats a block of code indefinitely until a EXIT statement is encountered.

beginner

How does a WHILE loop work in PostgreSQL?

A WHILE loop repeats the code inside it as long as the given condition is true. It checks the condition before each iteration.

intermediate

What is the difference between a FOR loop and a WHILE loop in PostgreSQL?

A FOR loop iterates over a range or query result automatically, while a WHILE loop repeats based on a condition you write and check manually.

beginner

How do you exit a LOOP in PostgreSQL?

You use the EXIT statement to stop the LOOP when a certain condition is met.

beginner

Write a simple example of a FOR loop in PostgreSQL that prints numbers from 1 to 5.

DECLARE i INT; BEGIN FOR i IN 1..5 LOOP RAISE NOTICE 'Number: %', i; END LOOP; END;

Which statement correctly exits a LOOP in PostgreSQL?

A END LOOP;

B EXIT;

C STOP;

D BREAK;

In PostgreSQL, the EXIT statement is used to leave a LOOP.

What does a WHILE loop do before each iteration?

A Checks if the condition is true

B Increments a counter automatically

C Executes the loop body once unconditionally

D Exits the loop

A WHILE loop checks the condition before running the loop body each time.

Which loop type automatically iterates over a range in PostgreSQL?

A FOR

B LOOP

C WHILE

D IF

FOR loops in PostgreSQL can iterate automatically over a range or query results.

What keyword starts a loop block in PostgreSQL?

A DO LOOP

B BEGIN LOOP

C START LOOP

D LOOP

The LOOP keyword starts a loop block in PostgreSQL.

How do you write a FOR loop to iterate from 1 to 10 in PostgreSQL?

A FOR i IN 1 TO 10 LOOP

B FOR i FROM 1 TO 10 LOOP

C FOR i IN 1..10 LOOP

D FOR i BETWEEN 1 AND 10 LOOP

The correct syntax uses two dots: FOR i IN 1..10 LOOP

Explain how LOOP, WHILE, and FOR loops differ in PostgreSQL and when you might use each.

Think about how each loop controls repetition and what stops it.

Describe how to safely exit a LOOP in PostgreSQL and why it is important.

Consider what happens if you forget to exit a loop.