Learning PostgreSQL 11 - Third Edition

The WHILE loop statement

The WHILE statement keeps executing a block of statements while a particular condition is met. Its syntax is as follows:

[ <<label>> ]WHILE boolean-expression LOOP    statementsEND LOOP [ label ];

The following example uses the while loop to print the days of the current month:

DO $$DECLARE first_day_in_month date := date_trunc('month', current_date)::date; last_day_in_month date := (date_trunc('month', current_date)+ INTERVAL '1 MONTH - 1 day')::date; counter date = first_day_in_month;BEGIN WHILE (counter <= last_day_in_month) LOOP RAISE notice '%', counter; counter := counter + interval '1 day'; END LOOP;END;$$ LANGUAGE plpgsql;