controlling search relevance in MySQL

What is the possible ways to control search engine reverence in MySQL? let us assume we are building a search engine for a small web store where buyers can add there stuff for sell. The table is:

CREATE TABLE `products` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
`title` VARCHAR( 100 ) NOT NULL ,
`date` DATE NOT NULL ,
`buyer_level` INT( 2 ) NOT NULL ,
FULLTEXT (
`title`
 )
) ENGINE = MYISAM ;

I want to give a weight for the following factors:

• title : Matching the input search keyword with the title,weight = 10.
• Buyer_level : higher is better. the level for the golden buyer is 10,bad buyers is 1. weight =5.
• Date : newer is better. weight =5.

The question is,how do we make MySQL output the result based on the value of the weight?

Example:

if we have the follo开发者_运维知识库wing rows in the table:

1, IPhone, 22-5-2010,9

2, IPhone, 22-5-2010,1

if the user search about Iphone, the first row should comes first and the second row should becomes the last because the first one have more wight than the second one.

---

select IF(title='IPhone',10,0)+buyer_level from products;

Date is a bigger problem, with CURRENT_DATE() you can compare to the current date. But you have to find a good middle way between new dates don't influences your metric to much and old dates don't influences your metric enough.

---

Can't really put weight on date unless you more closely define 'newer'.

ORDER BY (
  IF(title LIKE '%search%' ,10,0) 
  + buyer_level
  + IF(5 - DATEDIFF(NOW(),date) < 0,0,5 - DATEDIFF(date,NOW()))
  ) DESC,