Question

I want to fetch data from three tables that are Products, Attributes and features
One product may have multiple features and attributes

I am using query

select * 
from products p, features f, attributes a 
where p.id =1 and p.id = f.id and p.id = a.id

I want to know if the query is ok ???

Answer 1

You are using ANSI SQL-89 syntax. But I’ll recommend to use ANSI SQL-92 syntax. Example of that is below:

SELECT * 
FROM products p 
         INNER JOIN features f 
                ON p.id = f.id 
         INNER JOIN attributes a 
                ON p.id = a.id
where p.id =1

in that way you have to explicitly define their relationship (the ON clause) in order to avoid syntax error. The ANSI SQL-89 syntax is prone to error and you might not notice it because it will not produce an error. Example

SELECT * 
FROM products p, features f, attributes a
where p.id =1

Without defining the relationship field, it will still execute but gives you invalid result. From INNER JOIN, it is now CROSS JOIN

Additional Information

        Read something here
        MySQL JOIN Tutorials