關(guān)于表的命名
DELETE t1 FROM tdb_goods AS t1 LEFT JOIN (SELECT goods_id,goods_name FROM tdb_goods GROUP BY goods_name HAVING count(goods_name) >= 2 ) AS t2 ?ON t1.goods_name = t2.goods_name ?WHERE t1.goods_id > t2.goods_id;
我一直很不理解“AS t2”是什么意思，t2指的是表tdb_goods 嗎？
2017-05-11
t2是前面(SELECT goods_id,goods_name FROM tdb_goods GROUP BY goods_name HAVING count(goods_name) >= 2 ) 輸出數(shù)據(jù)(也可以當(dāng)成一個(gè)表)的別名