mysql - inner join和普通的多表选择有什么区别？

Question

我有两个问题:

SELECT m.id, m.name, f.type, c.id 
FROM main AS m, filter AS f, city AS c 
WHERE m.id = f.id AND c.name = m.city;

和

SELECT m.id, m.name, f.type, c.id 
FROM main AS m 
INNER JOIN filter as f ON m.id = f.id 
INNER JOIN city AS c ON c.name = m.city;

两者都应该给我相同的输出集。我为一小组值运行它们并且工作正常，但是当我为一组非常大的值运行它们时，两者都返回非常不同的行数(第一个返回 ~500K 行，而第二个返回 ~65K 行).这两个查询有什么区别吗？

[编辑]:

我正在使用 mysql 作为 RDBMS。

Answer 1

即使查询 #2 是推荐的标准。两个查询应返回相同的结果。

我的建议。比较那些分开的连接查询

SELECT m.id, m.name, f.type
FROM main AS m, filter AS f
WHERE m.id = f.id;

SELECT m.id, m.name, f.type
FROM main AS m 
INNER JOIN filter as f ON m.id = f.id;

然后

SELECT m.id, m.name, c.id 
FROM main AS m, city AS c 
WHERE c.name = m.city;

SELECT m.id, m.name, f.type, c.id 
FROM main AS m 
INNER JOIN city AS c ON c.name = m.city;

如果有任何不同，请告诉我们。 (应该没有)