php and mysql help?

I have two columns in my database - rating and matches

I have a third column called average

I want to cycle through EVERY row in the database and work out the average of the values rating and matches and place the result in average.

A bit of help? Thanks

I don't think I really understand your setup.

You've got your table (database) set up like this:
match - rating - average

How do you want to fill that average with only 1 rating? Or is there duplicate rows for 1 match with different ratings, and you want the average of them all to be in all rows of that match? OR does the "rating" field contain multiple ratings?

The rating field is many ratings added up from multiple "matches." The amount of matches is found in the "matches" column.

Basically before doing some work to the average data I need to make sure the value is correct and up to date. So I need a peice of code that goes through each row in the table and works out the average and places the correct value into "average."

Code:
rating | matches | average
---------------------------
     1 |       3 |       2?
---------------------------
     0 |      10 |       5?
---------------------------
     3 |       3 |       3?
---------------------------
     5 |      15 |      10?
Am I on the right track with how you want it to work? e.g. the average of 0 and 10 is 5 etc..

Yes. I know how to do the average calculation but am unsure on how to do a loop which runs through every row in the database and does this average calculation.

Code:
UPDATE mytable SET average = (rating + matches) / 2

The average isn't correct like that though. Rating 5 over 15 matches isn't an average of 10? Or is it just wrong naming of your rows..

Lets say someone has been rated like this:

Match 1: 10
match 2: 8
Match 3: 9
Match 4: 2

There added rating is 29 over 4 games. So their average rating for the season so far is 7.25.

All I need is a little help explaining how I'd create a php loop that would take every row in the database and apply this calculation. I know how to do it for 1 row, but how is it done for every row?

Check out GROUP BY and AVERAGE().

Hey,

Read this tut: http://www.plus2net.com/sql_tutorial/sql_avg.php