Cykly

CREATE OR REPLACE FUNCTION myfunction(integer)
RETURNS integer AS '
  DECLARE
   nm ALIAS FOR $1;
    cub INTEGER;
  BEGIN
   cub:=nm;
    WHILE cub <=3 LOOP
      cub := cub * cub * cub;
    END LOOP;
    RETURN cub;
  END;
' LANGUAGE 'plpgsql';

SELECT myfunction(2);

-- 10. Cykly, FOR
 [ <<label>> ]
  FOR identifier IN [ REVERSE ] expression1 .. expression2  LOOP
      statement;
      [...]
  END LOOP;

  CREATE OR REPLACE FUNCTION myfunction(dt DATE)
RETURNS INTEGER
AS
$$
DECLARE ddt DATE;
        num  INTEGER;
        x  INTEGER;
BEGIN
   ddT := dt;
   x := EXTRACT(MONTH FROM dt);
   FOR i IN 1 .. 31
   LOOP
      num := i;
      EXIT WHEN EXTRACT(MONTH FROM ddt + i * INTERVAL '1 DAY') <> x;
   END LOOP;
   RETURN num-1;
END;
$$
LANGUAGE PLPGSQL;

SELECT myfunction(CURRENT_DATE);