mysql流控制語句（LOOP, REPEAT, WHILE）

1.loop
語法：

[:] LOOP
    
END LOOP []begin_labelstatement_listend_label

例子：
CREATE PROCEDURE doiterate(p1 INT)
BEGIN
  label1: LOOP
    SET p1 = p1 + 1;
    IF p1 < 10 THEN
      ITERATE label1;//  can appear only within , , and  statements.  means 「start the loop again.」
    END IF;
    LEAVE label1;//  can be used within  or loop constructs (, , ).
  END LOOP label1;
  SET @x = p1;
END;
2.repeat 
語法ITERATELOOPREPEATWHILEITERATELEAVEBEGIN ... ENDLOOPREPEATWHILE

[:] REPEAT
    
UNTIL 
END REPEAT []

例子：begin_labelstatement_listsearch_conditionend_label

mysql> 

mysql> 
    -> 
    ->   
    ->   
    ->     
    ->   
    -> 
    -> 
Query OK, 0 rows affected (0.00 sec)

mysql> 
Query OK, 0 rows affected (0.00 sec)

mysql> 
+------+
| @x   |
+------+
| 1001 |
+------+
1 row in set (0.00 sec)

3.while
語法delimiter //CREATE PROCEDURE dorepeat(p1 INT)BEGINSET @x = 0;REPEATSET @x = @x + 1;UNTIL @x > p1 END REPEAT;END//CALL dorepeat(1000)//SELECT @x//

[:] WHILE  DO
    
END WHILE []begin_labelsearch_conditionstatement_listend_label

例子：

CREATE PROCEDURE dowhile()
BEGIN
  DECLARE v1 INT DEFAULT 5;

  WHILE v1 > 0 DO
    ...
    SET v1 = v1 - 1;
  END WHILE;
END;

4.label標記語法

[:] BEGIN
    []
END []

[:] LOOP
    
END LOOP []

[:] REPEAT
    
UNTIL 
END REPEAT []

[:] WHILE  DO
    
END WHILE []begin_labelstatement_listend_labelbegin_labelstatement_listend_labelbegin_labelstatement_listsearch_conditionend_labelbegin_labelsearch_conditionstatement_listend_label