更新庫存後,再進行庫存檢查,如果庫存爲負數,則執行事務的回滾。
begin();//開始一個事物處理開始
$sql = "UPDATE ".$GLOBALS['a']->table('seconds_kill')."
SET kill_stock = kill_stock - 1
WHERE sk_id='".$sk_id."' LIMIT 1" ;
$GLOBALS['db']->query($sql);
$sql = "SELECT kill_stock ".
" FROM ".$GLOBALS['a']->table('seconds_kill').
" WHERE sk_id='".$sk_id."'";
$kucun = $GLOBALS['db']->getOne($sql);
if($kucun<0)
{
rollback();
show_message('很抱歉,您購買的商品庫存不足! ', '返回', '', 'error');
die();
}else{
commit();
}
//開始
function begin()
{
$GLOBALS['db'] -> query("set autocommit=0");//設置自動提交
$GLOBALS['db'] -> query("begin");//事務開始
}
//提交
function commit()
{
$GLOBALS['db'] -> query("commit");//提交
$GLOBALS['db'] -> query("set autocommit=1");
}
//回滾
function rollback()
{
$GLOBALS['db'] -> query("rollback");//回滾所做的數據庫更改
$GLOBALS['db'] -> query("set autocommit=1");
}