使用php和mysql构建网站的更有效方法（已取消或已查询？）

Question

Background:

I've just started learning php to create a website to display user data from a betting program held in a mysql database.

The program in question (An IRC bet bot client written in python) originally used .csv text file arrays to hold user data. However I realized that this method of data storage really wasn't scale-able and held a lot of data in memory (thus required lots of file writes and flat text file searches).

I re-implemented the program to use a mySQL database instead. I'm currently re-writing the website.

Is it best that for every user I query the mySQL database once for each variable stored (thus hundreds of queries need to construct a user list page)? Or should I query the database once but the data into an array and cherry pick the variables out of that array that I need to display? Thus only querying once but holding more data in memory and doing much more server based processing.

The original website (That still works using text.csv files) can currently be found here: http://xcoins.co.uk (However this will soon be updated with the mysql based version (hopefully))

Question:

Is it better to query a mySQL database once per user get lots of data and sort it using php to display a list of users sorted by a value (some of the returned data from the query may be discarded or maybe cached). OR should I query the database lots of times for each variable of user data I need on a page but thus it will only grab what data is needed (but would require around 100 queries to be sent an received to display a single user list page)?

How many queries are generally acceptable to display a single webpage with lots of data on it?

Answer 1

The common way is to retrieve as much information as you need for a given page (but no more), and to use this result set to populate the page.

So, to create the "customer profile" page, you might run a query like:

select p.name, 
       p.address, 
       sum(t.amount) as balance
from   profile p, 
       transactions t
where  p.id = ?
and    p.id = t.id

(Apologies for archaic join syntax - old habits die hard).

This would give you a PHP result set, which you'd print to the page in the appropriate place.

Of course, often you cannot retrieve all the data you need in a single query, either because there isn't a natural join (eg showing the number of active users on the system), or for performance/complexity reasons. In this case, you'd write individual queries for those data elements.

You may want to look at PHP frameworks which abstract away a lot of this stuff for you.