MySQL 存儲過程語法 Python 變量傳遞

Question

假設我在 MYSQL 工作台中有一個存儲過程：

CREATE DEFINER=`root`@`localhost` PROCEDURE `calculateLeadTime`()
BEGIN
    SET @lastDate = (SELECT sessionDate FROM stock 
    WHERE product = (%s)
    ORDER BY stocksessionID DESC LIMIT 1);

    SET @secondLastDate = (SELECT sessionDate FROM stock WHERE product = (%s)
    ORDER BY stocksessionID DESC LIMIT 1, 1);

    SET @leadTime = (SELECT DATEDIFF(@lastDate, @secondLastDate));
    SET @lastStockSessionID = (SELECT stocksessionID
    FROM stock WHERE product = (%s) ORDER BY stocksessionID DESC LIMIT 1);

    UPDATE stock SET leadTime = (@leadTime)
    WHERE stocksessionID = @lastStockSessionID;
END

我在存儲過程中使用什么語法來替換 (%s)，因為它會產生錯誤？ 我的目標是通過 Python 調用它並將變量傳遞到 (%s) 位置。

Answer 1

試試這個：

CREATE DEFINER=`root`@`localhost` PROCEDURE `calculateLeadTime`(
IN  product varchar(64))
BEGIN
    SET @lastDate = (SELECT sessionDate FROM stock 
    WHERE product = (%s)
    ORDER BY stocksessionID DESC LIMIT 1);

    SET @secondLastDate = (SELECT sessionDate FROM stock WHERE product = (%s)
    ORDER BY stocksessionID DESC LIMIT 1, 1);

    SET @leadTime = (SELECT DATEDIFF(@lastDate, @secondLastDate));
    SET @lastStockSessionID = (SELECT stocksessionID
    FROM stock WHERE product = (%s) ORDER BY stocksessionID DESC LIMIT 1);

    UPDATE stock SET leadTime = (@leadTime)
    WHERE stocksessionID = @lastStockSessionID;
END

並在調用程序時

cursor.execute('{CALL [calculateLeadTime](?)}',
              ('value'))

或者

cursor.callproc('calculateLeadTime', ['product_name, ])

傳遞您產品的價值

Answer 2

您需要在存儲過程中定義一個變量並使用它而不是%s 。

CREATE DEFINER=`root`@`localhost` PROCEDURE `calculateLeadTime`(
in_product varchar(255)
)
BEGIN

DECLARE v_last_date date;
DECLARE v_second_last_date date;
DECLARE v_lead_time int;

SELECT sessionDate into v_last_date 
FROM stock 
WHERE product = in_product
ORDER BY stocksessionID DESC 
LIMIT 1;

SELECT sessionDate into v_second_last_date 
FROM stock 
WHERE product = in_product
ORDER BY stocksessionID DESC 
LIMIT 1;

SELECT DATEDIFF(v_last_date, v_second_last_date) into v_lead_time;

UPDATE stock SET leadTime = v_lead_time
WHERE stocksessionID = (
  SELECT stocksessionID
  FROM stock 
  WHERE product = in_product 
  ORDER BY stocksessionID DESC 
  LIMIT 1
);

END