I have a web page coded in PHP. This page is for posting a request for services. All services are stored in two separate tables along with prices.
As the user selects various services I want to fetch prices for the selected service and show it on per service basis and also a grand total of all services.
How can we do this?
Rather than a database query for every service they tick, you could add all the variables into the page as hidden vairables, then use Javascript to add them up. This would be much less overhead.
I'm not totally sure what you're going for, but you can't actually fetch anything from MySQL with Javascript, but you can request a php script via xhr that will fetch the data, and then deal with it (add it up, etc.) via javascript.
If the number of services/prices isn't huge, you could load it all in to the page in the first place then use javascript to add things up and leave the server alone.
There are several javascript frameworks and libraries that make this sort of thing quite easy (xhr), have you looked into those?
http://mootools.net http://dojotoolkit.com http://jquery.com http://www.prototypejs.org
If your data is too complex to pre-load as ck suggested, you can create a PHP page that generates JSON as your output. Using a library like jQuery you could then pull that data into the page for handling.
Ajax a php page that will do the MySQL operations. Make sure to actually secure that stuff, escape the strings, and make sure to check if the command being sent is the one you actually want. Some users are smarter than the rest and may go 'Drop *' using your ajax method.
Not a very safe idea IMO, but if something use Ajax.