Mysql查询更新行并使用相同的查询返回新值

Question

我有这个简单的查询来更新产品数量：

$updprqty='UPDATE products set     
available_qty = available_qty - '.$qty.' 
WHERE id = '.$pid.'';    

我还应该添加什么，以便获得available_qty的新值？ 感谢

Answer 1

您也可以查看此链接，您可能会对此有更多的了解

Get Updated Value in MySQL instead of affected rows

Answer 2

$updprqty='UPDATE products set     
available_qty = (select available_qty from products where id = ' .$pid . ') - '.$qty.' 
WHERE id = '.$pid.'';  

介绍别名

$updprqty='update products set available_qty =  x.available_qty from (select available_qty, id from products) - '.$qty.' where id = ' .$pid . ')  as x where id = x.id';