Introduction
Syntax of PL/pgSQL
Function parameters
Instruction
Brilliant! You already know how to create and use IF statements, so let's move on to the next topic: loops. We'll start with the WHILE loop.
A WHILE loop repeats a sequence of statements as long as the given expression evaluates to true. See the example below:
CREATE FUNCTION print_preceding()
RETURNS void AS $$
DECLARE
counter smallint := 10;
BEGIN
WHILE counter > 0 LOOP
RAISE NOTICE 'Current counter value: %', counter;
counter := counter - 1;
END LOOP;
END;
$$ LANGUAGE plpgsql;
The counter is initially set to 10, and the current counter value is printed in the WHILE loop. The counter value is decreased by 1 in each iteration until it's equal to 0.
The final output will look like this:
Current counter value: 10 Current counter value: 9 Current counter value: 8 Current counter value: 7 Current counter value: 6 Current counter value: 5 Current counter value: 4 Current counter value: 3 Current counter value: 2 Current counter value: 1
Exercise
Create a WHILE loop that prints (by raising notices) the square of integer from 1 to 10, inclusive. The final output should look like this:
1 to the power of 2 is equal to: 1 2 to the power of 2 is equal to: 4 3 to the power of 2 is equal to: 9 4 to the power of 2 is equal to: 16 5 to the power of 2 is equal to: 25 6 to the power of 2 is equal to: 36 7 to the power of 2 is equal to: 49 8 to the power of 2 is equal to: 64 9 to the power of 2 is equal to: 81 10 to the power of 2 is equal to: 100
Name the function print_squares.
Stuck? Here's a hint!
Use the power(counter, 2) function.
