Question

Possible Duplicate:
INNER JOIN ON vs WHERE clause

I started as web developer about 1 year ago. Since then I’ve gone through PHP, mySQL, Javascript, jQuery, etc. I think I’ve learned some things in this time. But when it comes to SQL I’m a real noob. I just do a couple of SELECT, INSERT, UPDATE, and using some functions like SUM or UNIX_TIMESTAMP, etc.

I’ve come across the JOIN functions, and it seems to be pretty useful, but I don’t see the difference of using JOIN or some WHERE clauses to “join” the data betwwen tables.

I read this article (spanish) about join. and I can’t really see the usefulness of it. For example:

Assuming this dataset:

id nombre       id  nombre
-- ----         --  ----
1  Pirata       1   Rutabaga
2  Mico         2   Pirata
3  Ninja        3   Darth Vader
4  Spaghetti    4   Ninja

Wouldn’t this query: SELECT * FROM TablaA INNER JOIN TablaB ON TablaA.name = TablaB.name produce the same results as SELECT * FROM TablaA, TablaB WHERE TablaA.name = TablaB.name ?

Answer 1

Yes, they will produce the same result, however, SELECT * FROM TablaA, TablaB WHERE TablaA.name = TablaB.name is an older method of performing a join that does not meet the SQL-92 standard. It is also a lot more difficult to read once your queries start to become very complex. It is better to stick with the explicitly declared INNER JOIN format.