Syntax
------

ITERATE label

ITERATE can appear only within LOOP, REPEAT, and WHILE statements. ITERATE
means "do the loop again", and uses the statement's label to determine which
statements to repeat. The label must be in the same stored program, not in a
caller procedure.

If you try to use ITERATE with a non-existing label, or if the label is
associated to a construct which is not a loop, the following error will be
produced:

ERROR 1308 (42000): ITERATE with no matching label: <label_name>

Below is an example of how ITERATE might be used:

CREATE PROCEDURE doiterate(p1 INT)
BEGIN
 label1: LOOP
  SET p1 = p1 + 1;
  IF p1 < 10 THEN ITERATE label1; END IF;
  LEAVE label1;
 END LOOP label1;
 SET @x = p1;
END

URL: https://mariadb.com/kb/en/iterate/