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python - 用于 Python 变量传递的 MySQL 存储过程语法

问题描述

假设我在 MYSQL Workbench 中有一个存储过程：

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

我在存储过程中使用什么语法来替换 (%s)，因为它会产生错误？我的目标是通过 Python 调用它并将变量传递到 (%s) 位置。

标签： pythonmysqlsqlpython-3.xprocedure

解决方案

您需要在存储过程中定义一个变量并使用它来代替%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

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