What is the best practice for storing and calculating average ratings in a PHP script?

When storing and calculating average ratings in a PHP script, it is best practice to store the total number of ratings and the sum of all ratings in addition to the average rating itself. This allows for easy updates when a new rating is added or an existing rating is updated. To calculate the average rating, simply divide the sum of all ratings by the total number of ratings. 

// Example of storing and calculating average ratings in PHP

// Retrieve current total number of ratings, sum of ratings, and average rating from database
$total_ratings = 10;
$sum_of_ratings = 45;
$average_rating = $sum_of_ratings / $total_ratings;

// Add a new rating
$new_rating = 5;
$total_ratings++;
$sum_of_ratings += $new_rating;

// Recalculate average rating
$average_rating = $sum_of_ratings / $total_ratings;

// Update database with new total number of ratings, sum of ratings, and average rating
// UPDATE ratings_table SET total_ratings = $total_ratings, sum_of_ratings = $sum_of_ratings, average_rating = $average_rating WHERE id = $item_id;

Keywords

database SQL aggregation rating system algorithm

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