## Calculate avg age of multiple users?!?!

I'm trying to figure ot the avareage age of all users in a certain group.

This is how I calculate 1 user:
PHP Code:
``` \$sql="SELECT * FROM ".\$prefix."_users WHERE group = 1"; \$result = mysql_query(\$sql); while(\$row = mysql_fetch_array(\$result)){    \$birthday = \$row['birthday']; // 1970-05-08 //    list(\$year,\$month,\$day) = explode("-",\$birthday);    \$year_diff  = date("Y") - \$year;    \$month_diff = date("m") - \$month;    \$day_diff   = date("d") - \$day;    echo 'Age: '.\$year_diff; }  ```
As you can see I calculate the age outside the query... I think I have to doit within the query...

Any help is apreciated...