SEO

#1 (**permalink**) 02-28-2008, 08:51 AM

Hello! Can someone verify this for me please.

Should these 2 statments return the same result ? The 2nd one is the
original, the first one is my re-write. Thanks :

SELECT orders_status, paypalipn_txn . *
FROM orders
INNER JOIN paypalipn_txn ON item_number = orders_id
WHERE customers_id = 4417
ORDER BY date_purchased DESC LIMIT 1

and :

SELECT o.orders_status,p.*
FROM orders o
LEFT JOIN paypalipn_txn p on p.item_number = o.orders_id
AND o.customers_id = 4417 order by o.date_purchased desc limit 1

#2 (**permalink**) 02-28-2008, 08:51 AM

It doesn't appear to be the same...

The INNER JOIN will return only orders that have a corresponding
paypalipn_txn record and belong to customer 4417.

The original LEFT JOIN returns all orders that belong to customer 4417.
If there's a paypalipn_txn record matching the join criteria, those
fields will be filled in, otherwise they will appear as NULL.

Some more info:

http://download-uk.oracle.com/docs/c...s7.htm#2054014
http://dev.mysql.com/doc/refman/5.0/en/join.html

Syl wrote:
> Hello! Can someone verify this for me please.
>
> Should these 2 statments return the same result ? The 2nd one is the
> original, the first one is my re-write. Thanks :
>
> SELECT orders_status, paypalipn_txn . *
> FROM orders
> INNER JOIN paypalipn_txn ON item_number = orders_id
> WHERE customers_id = 4417
> ORDER BY date_purchased DESC LIMIT 1
>
> and :
>
> SELECT o.orders_status,p.*
> FROM orders o
> LEFT JOIN paypalipn_txn p on p.item_number = o.orders_id
> AND o.customers_id = 4417 order by o.date_purchased desc limit 1

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SEO

two statments - same result ????