SQL Best Practise

Isolating indexed field
//Bad Idea.
Where TO_DAYS(order_created) - TO_DAYS(CURRENT_DATE())>= 7

//Better Idea. CURRENT_DATE() not working for query cache
Where order_created >= CURRENT_DATE() - INTERVAL 7 DAY

//Best Idea
Where order_created >= '11/11/2009' - INTERVAL 7 DAY


Using calculated field
//Bad idea
WHERE email_address LIKE '%.com';

//Better idea
ALTER TABLE CUSTOMERS
ADD COLUMN rv_email_address VARCHAR(80) NOT NULL;
UPDATE customers SET rv_email_address = REVERSE(email_address);
CREATE INDEX ix_rv_email ON customer (rv_email_address(20));

DELIMITER ;;
CREATE TRIGGER trg_bi_cust BEFORE INSERT ON customers
FOR EACH ROW BEGIN
SET NEW.rv_email_address=REVERSE(NEW.email_address);
END;;

//same trigger for BEFORE UPDATE...
//Then SELECT on the new field...
WHERE r_email_address LIKE CONCAT(REVERSE('.com'),'%');

J2ME HttpConnection issue

J2ME HttpConnection issue when testing with Digi telco and Sony Ericsson W810i

I am wondering why Lwuit-Makeover is able to connect but my own application can not. Then i found out that my application need to run in Internet setting but Lwuit-Makeover just need WAP setting.

If request connection setting from telco, they will send you the following setting.

• Digi Streaming
• Digi Internet
• Digi MMS
• Digi WAP

My personal experience about requesting the Digi internet setting. I had make more than 10 times to request Digi Internet setting. First few time failed was because of the "data account full...". Then i browsed to data comm.->data account to delete all the settings. After that, finally i can install successfully with those settings BUT there was no internet setting... So I kept on calling them to send me the internet setting. After few times request i met a guy who suggested to send only internet setting and not like previously send all settings(MMS,WAP,STREAMING, INTERNET...) in once. It work!!! Thanks guy.

Lwuit-Makeover

• "Setting for java" can be WAP setting.
• Internally this application use com.sun.me.web.request api and Get method to make connection.

My own application

• "Setting for java" does not work with WAP setting. It need internet setting.
• I use (HttpConnection) Connector.open("http://.."); and writebyte method to make connection.

Is it mean that WAP only work for GET and internet setting is able to work with writebyte? I still need time to figure out what so special in com.sun.me.web.request.

Reference
Avoid Connection Problems with Your Java Applications