About Donald Campbell Expertise I can answer questions from general MySQL setup, and programming. I am well-versed in PHP, and can therefore answer more specific questions regarding MySQL interaction. Also, I can answer questions regarding safe and secure use of MySQL databases with dynamic websites.
Experience I have worked as a website design and technical writing consultant for 2 years now. I have experience with MySQL and PHP and programming dynamic websites using PHP to interact with a MySQL database.
Organizations I am currently CEO of Campbell Productions Software, Co.
Question Sir,
Can u pls tell me where we have to use inner join.The result after using cartesian product and inner join gives one of the same result.So i m unable to understand vch one is better in terms of performance and optimisation.
my query was:
INNER JOIN:
select * from aw_latest_quotes as alq
inner join aw_exchanges as ae on alq.exchange_code = ae.exchange_code
CARTESIAN PRODUCT:
select * from aw_latest_quotes as alq
, aw_exchanges as ae where alq.exchange_code = ae.exchange_code
Also tell me when to use outer join and how its differnt from inner join.
Thanks and Regards
Ankit jain
Answer Hello!
Inner join allows you specifically state a join clause, like alq.exchange_code = ae.exchange_code. The cartesian product is less efficient, because it first joins every possible combination of rows, and then filters the results to match your join clause.
An outer join, when compared to an inner join, displays all information, even if the information does not have an equivalent in the joined field. A great example and demonstration can be found on this page:
