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

建索引
order_isdelete goods_type order_no goods_id
这几个字段，考虑下怎么建索引优化查询。

Answer 2

where group by select 都尽量在索引上做吧

Answer 3

1. 尽量不要用JOIN,将功能从SQL迁移到代码层处理

2. 建立索引