Question

所以我写了这个小的存储函数，它应该会给我带来一个juiceorder的成本。但是，我在弄清楚为什么特别是它不起作用时遇到了一些麻烦。任何帮助将不胜感激

DELIMITER $$

CREATE DEFINER=`root`@`localhost` FUNCTION `juiceOrderCost`(p_id INT) RETURNS double
BEGIN
DECLARE cost DOUBLE;
DECLARE i INT DEFAULT 0;
DECLARE numRows INT;
DECLARE numDone INT DEFAULT 1;
DECLARE cup_id INT DEFAULT 0;

DECLARE myCursor CURSOR for
    SELECT cupId FROM hasJuice WHERE orderID = p_id;

OPEN myCursor;
SELECT FOUND_ROWS() INTO numRows;

FETCH myCursor INTO cup_id;
WHILE numDone <= numRows DO

SET cost =  cost + juiceCupCost(cup_id);

FETCH myCursor INTO cup_id;

SET numDone = numDone + 1;

END WHILE;

CLOSE myCursor;

返回成本; END

Answer 1

使用DECLARE CONTINUE HANDLER FOR NOT FOUND 访问https://dev.mysql.com/doc/refman/5.5/en/condition-handling.html

MySql - 如何摆脱无数据：零行获取

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