在Mysql存儲過程中的未知系統變量「no_more_data」

Question

我是使用mysql存儲過程的新手。有錯誤，我無法修復 這是我的代碼

DELIMITER $$ 

CREATE PROCEDURE `bankdb`.`charge`() 
BEGIN 
DECLARE idcust_val INT; 
DECLARE balance_val FLOAT; 
DECLARE productCd_val VARCHAR(10); 

DECLARE loop_cntr INT DEFAULT 0; 
DECLARE num_rows INT DEFAULT 0; 

DECLARE col_cur CURSOR FOR 
select c.cust_id, c.balance, c.product_cd 
from account c; 
DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_rows = TRUE; 

OPEN col_cur; 
select FOUND_ROWS() into num_rows; 

read_loop: LOOP 
FETCH col_cur INTO idcust_val, balance_val, productCd_val; 

IF no_more_rows THEN 
close col_cur; 
leave read_loop; 
END IF; 

IF productCd_val == 'SAV' || productCd_val == 'CD' THEN 
    IF balance_val == 2000 THEN 
      balance_val = balance_val-10; 
      UPDATE account SET avail_balance = balance_val 
      WHERE account_id =idcust_val; 
    END IF; 
END IF; 

IF productCd_val == 'CHK' || productCd_val == 'SAV' || productCd_val == 'MM' 
|| productCd_val == 'CD' THEN 
    balance_val = balance_val + (balance_val*0,05); 
    UPDATE account SET avail_balance = balance_val 
    WHERE account_id =idcust_val; 
ELSE 
    balance_val = balance_val - (balance_val*0,1); 
    UPDATE account SET avail_balance = balance_val 
    WHERE account_id =idcust_val; 
END IF; 
SET loop_cntr = loop_cntr + 1; 
END LOOP; 
END $$ 

DELIMITER ; 

當我執行它，MySQL查詢瀏覽器顯示的錯誤是這樣的：

腳本行：3未知的系統變量「no_more_rows」

請幫助我！

Answer 1

1. 一個變量no_more_rows必須被拖延，在程序主體開始時寫下一行。

   DECLARE no_more_rows INT DEFAULT 0;

2. 等於運算符是 '='

   IF productCd_val == 'SAV' 和等應IF productCd_val = 'SAV'

3. 使用SET指令到指定值，例如 -

   SET balance_val = balance_val - 10;