[begin_label:] BEGIN [statement_list] END [end_label] [begin_label:] LOOPstatement_listEND LOOP [end_label] [begin_label:] REPEATstatement_listUNTILsearch_conditionEND REPEAT [end_label] [begin_label:] WHILEsearch_conditionDOstatement_listEND WHILE [end_label]
Labels are permitted for BEGIN ... END blocks and for the LOOP, REPEAT, and WHILE statements. BEGIN ... END块、LOOP语句、REPEAT语句和WHILE语句允许使用标签。Label use for those statements follows these rules:这些语句的标签使用遵循以下规则：
begin_label must be followed by a colon.begin_label后面必须跟一个冒号。
begin_label can be given without end_label. begin_label可以不用end_label。If 如果存在end_label is present, it must be the same as begin_label.end_label，则必须与begin_label相同。
end_label cannot be given without begin_label.end_label，则不能给出begin_label。
Labels at the same nesting level must be distinct.同一嵌套级别的标签必须是不同的。
Labels can be up to 16 characters long.标签最长可达16个字符。
To refer to a label within the labeled construct, use an 要引用已标记构造中的标签，请使用ITERATE or LEAVE statement. ITERATE语句或LEAVE语句。The following example uses those statements to continue iterating or terminate the loop:以下示例使用这些语句继续迭代或终止循环：
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. 块标签的范围不包括块内声明的处理程序的代码。For details, see Section 13.6.7.2, “DECLARE ... HANDLER Statement”.有关详细信息，请参阅第13.6.7.2节，“DECLARE ... HANDLER语句”。