当客户 select 产品使用 - NodeJS/MySQL 时，努力使用 (connection.query(update...)) 更新值

Question

每次客户在 main_product_info 购买时，我希望减少库存数量 (stockQuantity)。

我正在尝试使用以下代码，但它似乎无法正常工作，我是 DB 的新手，所以不确定我是否使用了正确的代码。

另外，在下面的代码中，我直接将 quantity 更新为 productNumner，或者我应该使用 join（我几乎没有看到 post，但无法理解）并包括 main_product_sub_category（因为它有主键），只是想了解正确的做法。

Error: stockQuantity 未定义。

有什么建议吗

 connection.query("UPDATE main_product_info SET stockQuantity=? WHERE main_product_info.producNumber=?", [stockQuantity - 1, checkQuantity], function (err, result) {} 
// here  i am looking to decrese stockQuantity by 1

-main_product_info

-Snippet 代码使用 show create table,

mysql> SHOW CREATE TABLE main_Products_category;
+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table                  | Create Table                                                                                                                                                                                                     |
+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| main_Products_category | CREATE TABLE `main_products_category` (
  `productId` int NOT NULL AUTO_INCREMENT,
  `productCategory` varchar(45) NOT NULL,
  PRIMARY KEY (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=105 DEFAULT CHARSET=utf8 |
+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> SHOW CREATE TABLE main_products_sub_category;
+----------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table                      | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+----------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| main_products_sub_category | CREATE TABLE `main_products_sub_category` (
  `main_Products_sub_category_id` varchar(45) NOT NULL,
  `main_Products_sub_category_name` varchar(45) DEFAULT NULL,
  `main_Products_category_productId` int NOT NULL,
  PRIMARY KEY (`main_Products_sub_category_id`),
  KEY `fk_main_Products_sub_category_main_Products_category1_idx` (`main_Products_category_productId`),
  CONSTRAINT `fk_main_Products_sub_category_main_Products_category1` FOREIGN KEY (`main_Products_category_productId`) REFERENCES `main_products_category` (`productId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+----------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SHOW CREATE TABLE main_product_info;
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table             | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| main_product_info | CREATE TABLE `main_product_info` (
  `producInfoId` varchar(45) NOT NULL,
  `productDescription` mediumtext,
  `stockQuantity` int DEFAULT NULL,
  `producNumber` int DEFAULT NULL,
  `price` varchar(255) DEFAULT NULL,
  `product_name` varchar(255) DEFAULT NULL,
  `main_Products_sub_category_main_Products_sub_category_id` varchar(45) NOT NULL,
  PRIMARY KEY (`producInfoId`),
  KEY `fk_main_Product_Info_main_Products_sub_category1_idx` (`main_Products_sub_category_main_Products_sub_category_id`),
  CONSTRAINT `fk_main_Product_Info_main_Products_sub_category1` FOREIGN KEY (`main_Products_sub_category_main_Products_sub_category_id`) REFERENCES `main_products_sub_category` (`main_Products_sub_category_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

Answer 1

您可以在 mysql 中直接执行，无需参数

 connection.query("UPDATE main_product_info SET stockQuantity= stockQuantity - 1 WHERE main_product_info.producNumber=?", [checkQuantity], function (err, result) {} 
// here  i am looking to decrese stockQuantity by 1

当客户 select 产品使用 - NodeJS/MySQL 时，努力使用 (connection.query(update...)) 更新值

Struggling to Updating the value using (connection.query(update...)) when customer select the product using - NodeJS/MySQL

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