NominationP/preventOverSold

prevent over sold in php with mysql || redis

Prevent Over Sale

Mysql

1. code running sort

    // mysql innodb ==> update ==> row lock ( Exclusive lock )

    $sql = "update store set amount = amount-1 where goods_id = 12345";
    $this->db_instance->query($sql);
    $sql = "select amount from store where goods_id = 12345";
    $count = $this->db_instance->query($sql)->fetch_assoc()['amount'

2. all atomization

    // atomization with select && condition
    
    $sql = "update store set amount = amount-1 where goods_id = 12345 and amount >= 1";
    $re = $this->db_instance->query($sql);

Redis