Mysql學習筆記2

where查詢子句： select goods_id,cat_id,goods_name from goods where goods_id in (select max(goods_id) from goods group by cat_id)； 通過where的查詢子句能夠很好的擴張查詢效率，它是內層的查詢結果作爲外層的比較條件。 mysql> select goods_id,cat_id,g

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