Question

I am developing a trading site. Users will post some price, $100, $120 for certain products. And I wanted to display highest price for that product, which means current highest price will replace the previous highest price. Tables of mysql is:

user_email //The user who gives price for the product
product//The product name
price//The prices that users posted
chosen//it will be 1 if it is highest otherwise 0

What I wanted to do is that if a user posted $100 for, for example, a book and it is currently highest price (chosen is one for this user) and site displays it. Another user posts $120 for that book and it is now highest price (chosen is 1) and for the previous user’s chosen is 0. I could not figure out how to compare prices for certain products and change all of the lower prices chosen 0 for that product. How can i do this? Sorry i am new:(

Answer 1

You can use the MAX function from MySQL to get the highest number of a colomn. Example :

    SELECT MAX(field) FROM `table_name` 

You just need to add WHERE and it will confine the search fields.

After, you update everything else with something like this

    UPDATE `table_name` SET `field` = 0 WHERE `product` = "X" AND `id` != Y

X will be the product ID and Y will be the ID from the first query.