我将创建一个自定义表，存储a）进行评级的用户b）被评级的用户c）评级d）评级时间。在这四种方法之间，您应该能够以很少的开销或PHP处理来存储、聚合和有效地查询数据。

更新

note: this is pseudocode

function get_user_rating( $user_id ) {
    $rating = get_from_database(
        \'SELECT AVG(rating)
        FROM ratings_table
        WHERE user_being_rated = \'.$user_id
    );

    return $rating;
}

function add_user_rating( $rater, $rated, $rating ) {
    //check to see if there is already a rating to avoid duplicate records
    if( already_rated( $rater, $rated ) ) {
        //remove previous rating
        remove_rating( $rater, $rated );
    }
    //insert current rating
    insert_into_database(
        \'INSERT INTO ratings_table
        ( user_doing_rating, user_being_rated, rating, time ) VALUE
        ( \'.$rater.\', \'.$rated.\', \'.$rating.\', CURTIME() )\'
    );
}