Question

即使我尝试了很多事情，它仍然给我这个错误（在游标或处理程序声明之后的变量或条件声明 SQL语句）

sp必须使用光标

CREATE PROCEDURE monthly_sum (IN cardId INT(36), IN monthN INT, OUT sumV float)
BEGIN
DECLARE cursor_1 CURSOR FOR
SELECT SUM(purchased.amountPurchased)
FROM purchased
WHERE MONTH(purchased.dateUsed) = monthN AND purchased.purchasedCardId = cardId AND DAY(purchased.dateUsed) <=10;

DECLARE cursor_2 CURSOR FOR
SELECT SUM(purchased.amountPurchased)
FROM purchased
WHERE MONTH(purchased.dateUsed)  = monthN AND purchased.purchasedCardId = cardId AND DAY(purchased.dateUsed) <=20 AND DAY(purchased.dateUsed) >10;

DECLARE cursor_3 CURSOR FOR
SELECT SUM(purchased.amountPurchased)
FROM purchased
WHERE MONTH(purchased.dateUsed) = monthN AND purchased.purchasedCardId = cardId AND DAY(purchased.dateUsed) >20;

DECLARE percentage1, percentage2, percentage3 float default 0;

OPEN cursor_1;
FETCH cursor_1
INTO percentage1;
CLOSE cursor_1;

OPEN cursor_2;
FETCH cursor_2
INTO percentage2;
CLOSE cursor_2;

OPEN cursor_3;
FETCH cursor_3
INTO percentage3;
CLOSE cursor_3;
SET sumV = percentage1*0.01 + percentage2*0.02 + percentage1*0.03;

SELECT sumV;
END

预期的输出总和为前10天的1％，接下来10天的2％，本月其余天的3％

Answer 1

i添加了DECLARE percent1，percent2，percent3 float默认值0；一开始像karmens89一样评论我，它奏效了

Answer 2

可以使用select into来代替不必要地调用游标。由于游标用于逐行获取，但是在您的情况下，它只会生成一次。

CREATE PROCEDURE monthly_sum (IN cardId INT(36), IN monthN INT, OUT sumV float)
BEGIN

DECLARE percentage1, percentage2, percentage3 float default 0;

SELECT SUM(purchased.amountPurchased) INTO percentage1
FROM purchased
WHERE MONTH(purchased.dateUsed) = monthN 
AND purchased.purchasedCardId = cardId 
AND DAY(purchased.dateUsed) <=10;

SELECT SUM(purchased.amountPurchased) INTO percentage2
FROM purchased
WHERE MONTH(purchased.dateUsed)  = monthN 
AND purchased.purchasedCardId = cardId 
AND DAY(purchased.dateUsed) <=20 AND DAY(purchased.dateUsed) >10;

SELECT SUM(purchased.amountPurchased) INTO percentage3
FROM purchased
WHERE MONTH(purchased.dateUsed) = monthN 
AND purchased.purchasedCardId = cardId 
AND DAY(purchased.dateUsed) >20;

SET sumV = percentage1*0.01 + percentage2*0.02 + percentage1*0.03; # I think percentage3 to be added instead of percentage1
END

游标或处理程序声明后的变量或条件声明SQL语句（mysql）

2 个答案: