mysql 请教where a.id=b.id 和join on a.id=b.id 在效率上的区别-PHP Tutorial-php.cn

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mysql 请教where a.id=b.id 和join on a.id=b.id 在效率上的区别

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Jun 13, 2016 am 11:42 AM

idjoinnbsp

mysql求助请问where a.id=b.id 和join on a.id=b.id 在效率上的区别
下面是ecshop 的商品表和品牌表的查询，请问它们的查询效率有什么区别呢？
还有一个问题是 left join 和join的效率哪个高一点呢。
谢谢！！

<br />SELECT a.`goods_id` , a.`goods_name` , b.brand_name<br />FROM  `ecs_goods` AS a<br />LEFT JOIN ecs_brand AS b ON a.`brand_id` = b.`brand_id` <br />

<br />SELECT a.`goods_id` , a.`goods_name` , b.brand_name<br />FROM  `ecs_goods` AS a, ecs_brand AS b<br />WHERE a.`brand_id` = b.`brand_id`<br />

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