php - 比较不同表中的2个Mysql列并删除

Question

好的，所以我的问题是这样的

我有一个支持自动列出的拍卖网站，但是当拍卖自动列出时，它不会清除旧条目，所以我打算编写一些 php 代码并将其作为 cronjob 运行以清除之后所说的条目2天左右，引用的表是 probid_auctions & probid_auction_media，列是auction_id，我想获取 probid_auction_media 中的列auction_id，并将其与 probid_auctions 中的列auction_id进行比较，并删除 probid_auction_media 中不匹配的任何条目

现在测试

mysql_connect($host, $username, $password);
mysql_select_db("b1396hos_database1") or die( "Unable to select database");
$db->query("DELETE * FROM  probid_auction_media 
WHERE auction_id NOT IN (SELECT DISTINCT auction_id FROM probid_auctions");

Answer 1

使用这样的查询

DELETE
FROM probid_auction_media
WHERE auction_id NOT IN(SELECT
                      probid_auction_media.auction_id
                    FROM probid_auctions,
                      probid_auction_media
                    where probid_auctions.auction_id != probid_auction_media.auction_id);