mysql - 慢查詢如何優化

問題描述

mysql慢查詢語句該如何優化

SELECT * FROM `x_order` LEFT JOIN x_goods ON x_goods.goods_id = x_order.order_goodsid WHERE `order_isdelete` = 0 AND `goods_type` = 0 GROUP BY order_no

問題解答

建索引 order_isdelete goods_type order_no goods_id 這幾個字段，考慮下怎么建索引優化查詢。

where group by select 都盡量在索引上做吧

盡量不要用JOIN,將功能從SQL遷移到代碼層處理

建立索引