Re: Can't think of a subject...

kris p wrote:
>
> A question about SQL statement structure...
>
> I have a query with a number of joins and my question
> is does the order of the tables listed after the FROM
> have any impact in which order the tables are joined?
>
> What about the order of the statements after the WHERE
> clause, do they affect the order in which a statement
> is executed?
>
> Thanks,
> kristoff plasun

Generally (ie in the vast majority of cases) the answer is no.

If there are no statistics on those tables (eg num_rows in user_tables is null for the all of the tables in the query), then the order might be important.

Have a read about optimizers (rule and cost) in the performance tuning reference.

hth
connor

-- 
-------------------------------
Connor McDonald
http://www.oracledba.co.uk
Co-Author: "Mastering Oracle PL/SQL - Practical Solutions"