mysql–写sql的聪明方式Join

我正在探索某人的代码,我找到了这个查询.这个查询是使用join获取数据.但是没有使用内连接,外连接,左或右.程序员只需编写此查询.

我发现这是编写查询的SMART方式,如果这个查询是对的？

SELECT
a.*,b.*,c.*,d.*,e.*
FROM
property_photos a,property_promotions b,properties c, communities d,cities e
WHERE
a.property_id = b.property_id AND
a.property_id = c.id AND
(b.promotion_id =2 OR b.promotion_id =1) AND
a.mainphoto="Y" AND
d.id=c.community_id AND
e.id = c.city_id AND
a.featured_status = 1


这个查询是否正确？

这个查询是正确的,我认为,这是更好的编写查询的方法,因为它将节省大量磁盘空间而不是使用左连接/右连接像单词,这使得查询很长

聪明的方式

解决方法:

是的,没关系.它与INNER JOIN相同.

注意：

Which Syntax to Use? Per the ANSI SQL specification, use of the INNER
JOIN syntax is preferable. Furthermore, although using the WHERE

clause to define joins is indeed simpler, using explicit join syntax

ensures that you will never forget the join condition, and it can

affect performance, too (in some cases).

资料来源：Sam’s – MySQL Crash Course, page 139