13.6.2. Statement Label Syntax

[begin_label:] BEGIN    [statement_list]END [end_label][begin_label:] LOOP    statement_listEND LOOP [end_label][begin_label:] REPEAT    statement_listUNTIL search_conditionEND REPEAT [end_label][begin_label:] WHILE search_condition DO    statement_listEND WHILE [end_label]

Labels are permitted for BEGIN ... END blocks and for the LOOP, REPEAT, and WHILE statements. Label use for those statements follows these rules:

begin_label must be followed by a colon.
begin_label can be given without end_label. If end_label is present, it must be the same as begin_label.
end_label cannot be given without begin_label.
Labels at the same nesting level must be distinct.
Labels can be up to 16 characters long.

To refer to a label within the labeled construct, use an ITERATE or LEAVE statement. The following example uses those statements to continue iterating or terminate the loop:

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;END;

The scope of a block label does not include the code for handlers declared within the block. For details, see Section 13.6.7.2, "DECLARE ... HANDLER Syntax".