PHP代码 - 如何检查Mysql数据库中的重复条目

Question

I am working on Google checkout API notification URL. I want to apply a check in my php code which will see if transaction ID present in transaction table of my DB, it will exit not process.

I am struggling into applying here. Can somebody help?

I want to check if trasaction ID exists in table of DB it will exit, it will not process:

case "new-order-notification":  
    $sql = "
        UPDATE
            transactions
        SET
            remote_trans_id=\"".$_REQUEST["google-order-number"]."\", updated=NOW() 
        WHERE
        id=".$_REQUEST["shopping-cart_items_item-1_merchant-item-id"]
        ;
    execute($sql, $conn);
break;

Regards

Answer 1

Just use INSERT ON DUPLICATE KEY UPDATE. This way mySql will do the checking for you, if is a new transaction will enter it otherwise will update the existing entry.