MySQL 存储过程语法 Python 变量传递

Question

Suppose I have a stored procedure in MYSQL Workbench:

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

What syntax do I use in the stored procedure in replacement of (%s) as it produces an error? My goal is to call it via Python and pass variable's into the (%s) places.

Answer 1

Try this one:

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

and when calling the procedure

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

or

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

Pass the value of your product

Answer 2

You need to define a variable in the stored procedure and use that instead of %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