php和mysql中的双重查询 [英] double query in php and mysql

问题描述

我有一个简单的INSERT查询，它在事件点击按钮时运行，它获取变量并将它们插入到`order`表中。



我也会喜欢更新我的乐队表格，将股票减少1直到达到0然后显示空或售罄而不是进入负数例如：-6



知道什么乐队被选中我可以使用：

I have a simple INSERT query that is run on event click of a button, this gets variables and inserts them into `order` table.

I also would like to UPDATE my bands table to reduce the stock by 1 until it reaches 0 then show null or sold out rather than go into negative eg: -6

to know what band is selected I can use :

WHERE Band_id = $Band_id");

在同一声明中。



目前的INSERT看起来像：

in the same statement.

the current INSERT looks like :

"INSERT INTO orders (band_id,user_id,user_name,band_name,band_venue) VALUES('$Band_id', '$user_id', '$user_name', '$name', '$venue')";

**结论* *



需要改变我的INSERT以更新WHILE检查它当前选择的乐队。



**答案提供检查**



这个解决方案有提供得非常好而且很有意义，但我还不够熟练，无法理解为什么它不能正常运行。

**Conclusion**

Need to alter my INSERT to also UPDATE WHILE checking that its the current selected band.

**ANSWER PROVIDED CHECK**

this solution has been wonderfully provided and it makes sense but im not quite skilled enough to understand why its not functioning correctly.

$sql = "INSERT INTO orders (band_id,user_id,user_name,band_name,band_venue) VALUES('$Band_id', '$user_id', '$user_name', '$name', '$venue')";
     
     $sql_create ="CREATE TRIGGER tg_ai_orders
    		AFTER INSERT ON orders
    		FOR EACH ROW
    		  UPDATE bands 
       		  SET stock = stock - 1
       		  WHERE band_id = NEW.band_id";
    
    $sql_deleat = "CREATE TRIGGER tg_ad_orders
    		AFTER DELETE ON orders
    		FOR EACH ROW
     		 UPDATE bands 
      	     SET stock = stock + 1
             WHERE band_id = OLD.band_id";
    
    mysql_query ($sql, $sql_deleat, $sql_create, $linkme)
        or die ("could not add to database");

推荐答案

Band_id ）;

Band_id");

在同一声明中。



当前的INSERT如下：

in the same statement.

the current INSERT looks like :

"INSERT INTO orders (band_id,user_id,user_name,band_name,band_venue) VALUES('

Band_id'，'

Band_id', '

user_id'，'

user_id', '

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