ANSI SQL Syntax - What belongs to join-clause and what to where-clause

Question

Hello,
we currently have a discussion about the ANSI SQL Syntax where we do not agree what belongs to the join clause and what belongs to the where clause in an ANSI Sytnax SQL Query.
Lets say there is a query like this:
+SELECT *+
FROM employees emp, departments dept
WHERE emp.dept_country = dept.dept_country
AND emp.dept_name = dept.dept_name
AND dept.dept_type = 'HQ'
AND emp.emp_lastname = 'Smith'
Primary key of the departments table is on the columns dept_country, dept_name and dept_type. We have a Oracle database 10g.
Now I have rewritten the query to Ansi Syntax:
+SELECT *+
FROM employees emp
JOIN departments dept
ON emp.dept_country = dept.dept_country AND emp.dept_name = dept.dept_name
WHERE dept.dept_type = 'HQ'
AND emp.emp_lastname = 'Smith'
Another developer says that this is not completely correct, every filter on a column that belongs to the primary-key of the joined table has to be in the join clause, like this:
+SELECT *+
FROM employees emp
JOIN departments dept
+ON emp.dept_country = dept.dept_country AND emp.dept_name = dept.dept_name AND dept.dept_type = 'HQ'
WHERE emp.emp_lastname = 'Smith'
Can somebody tell me which on is correct?
Is there any definition for that? I couldn't find it in the Oracle Database definition.
I just found out the names of the ANSI documents here: http://docs.oracle.com/cd/B19306_01/server.102/b14200/ap_standard_sql001.htm#i11939
I had a look at the ANSI webstore but there you have to buy the PDF files. In my case thats exaggerated because both of the Queries work and i am just interessted if there is one correct way.
Thank you in advance
Marco

Answer 1

Hi,
As i guideline i would say, answer the question: should the result of the join be filtered or should only filtered rows be joined from a particular table?
This is helpful in the case of outer joins also, for inner joins it doesnt matters as said already be former posters, where there may be hughe semantical differences depending of where the predicates are placed.
From performance view, if we talk about oracle, take a look a the execution plans. You will see that there is (probably) no difference in case of inner joins. Even in case of outer joins the optimizer pushes the predicate as a filter towards the table if it semantically possible.
Regards