The next type of loop widely used in Postgres is the FOR loop.
A FOR loop iterates a specified number of times. The lower and upper bound of the range are evaluated once when entering the loop.
Below are some examples of integer FOR loops:
FOR i IN 1..10 LOOP /* i will take on the values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 within the loop */ END LOOP;
If the REVERSE keyword is specified, then the step value is subtracted, rather than added, after each iteration.
FOR i IN REVERSE 10..1 LOOP /* i will take on the values: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 within the loop */ END LOOP;
The iteration step is 1 by default or the value (if any) specified in the BY clause.
FOR i IN REVERSE 10..1 BY 2 LOOP /* i will take on the values: 10, 8, 6, 4, 2 within the loop */ END LOOP;
Create a function named print_odd_numbers() that prints (by raising notices) all odd integers between 20 and 1.
The final output should look like this:
Odd Number: 19 Odd Number: 17 Odd Number: 15 Odd Number: 13 Odd Number: 11 Odd Number: 9 Odd Number: 7 Odd Number: 5 Odd Number: 3 Odd Number: 1
You may go either way:
FOR ... LOOP with the step (BY 2).FOR ... LOOP with the IF statement and a modulo operator (counter % 2) to determine if a number is odd or even.Then, simply use the following:
RAISE NOTICE 'Odd Number: %', counter;
