mysql - 慢查询如何优化

Question

mysql慢查询语句该如何优化

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

Answer 1

建立索引
order_isdelete goods_type order_no goods_id
這幾個字段，考慮下怎麼建索引優化查詢。

Answer 2

where group by select 都盡量在索引上做吧

Answer 3

1. 盡量不要用JOIN,將功能從SQL移轉到程式碼層處理

2. 建立索引