Конкретен въпрос за PHP код

Здравейте, имам проблеми с едно PHP упражнение Става дума за функция, която се опитвам да напиша, целта е да пресмята срeдноаритметично от стойности, но те трябва да се вземат от друга таблица. Благодаря предварително на отзовалите се!

ето го и кода:

Програмата извежда таблица с име на филм, дата на издаване, гл актьор и тн. Целта е да се направи функция която извлича средно-аритметично от рейтингите на филма... Функциято дето ме тормози е тази подчертаната...

<?php

$link = mysql_connect("localhost","root","pass7")

or die(mysql_error());

mysql_select_db("moviesite")

or die (mysql_error());

/* Function to calculate if a movie made a profit,

loss or broke even */

function calculate_differences($takings, $cost) {

$difference = $takings - $cost;

if ($difference < 0) {

$difference = substr($difference, 1);

$font_color = 'red';

$profit_or_loss = "$" . $difference . "m";

} elseif ($difference > 0) {

$font_color ='green';

$profit_or_loss = "$" . $difference . "m";

} else {

$font_color = 'blue';

$profit_or_loss = "Broke even";

}

return "<font color=\"$font_color\">" . $profit_or_loss . "</font>";

}

/* Function to get the director's name from the people table */

function get_director() {

global $movie_director;

global $director;

$query_d = "SELECT people_fullname " .

"FROM people " .

"WHERE people_id='$movie_director'";

$results_d = mysql_query($query_d)

or die(mysql_error());

$row_d = mysql_fetch_array($results_d);

extract($row_d);

$director = $people_fullname;

}

/* Function to get the lead actor's name from the people table */

function get_leadactor() {

global $movie_leadactor;

global $leadactor;

$query_a = "SELECT people_fullname " .

"FROM people " .

"WHERE people_id='$movie_leadactor'";

$results_a = mysql_query($query_a)

or die(mysql_error());

$row_a = mysql_fetch_array($results_a);

extract($row_a);

$leadactor = $people_fullname;

}

function rating(){

global $rating;

$query_r = "SELECT review_rating " .

"FROM reviews " .

"WHERE review_movie_id='" .$_GET['movie_id']. "' ";

$results_r = mysql_query($query_r, $link)

or die(mysql_error());

while($row_r = mysql_fetch_row($results_r)){

$rating+=$row_r['review_rating'];

}

$num_rows_r=mysql_num_rows($row_d);

$rating/=$num_rows_r;

}

$movie_query = "SELECT * FROM movie " .

"WHERE movie_id ='" . $_GET['movie_id'] . "'";

$movie_result = mysql_query($movie_query, $link)

or die(mysql_error());

$movie_table_headings=<<<EOD

<tr>

<th>Movie Title</th>

<th>Year of Release</th>

<th>Movie Director</th>

<th>Movie Lead Actor</th>

<th>Movie Running Time</th>

<th>Movie Health</th>

<th>Ratings</th>

</tr>

EOD;

$review_table_headings=<<<EOD

<tr>

<th>Date of Review</th>

<th>Review Title</th>

<th>Reviewer Name</th>

<th>Movie Review Comments</th>

<th>Rating</th>

</tr>

EOD;

$review_query = "SELECT * FROM reviews " .

"WHERE review_movie_id ='" . $_GET['movie_id'] . "' " .

"ORDER BY review_date DESC";

$review_result = mysql_query($review_query, $link)

or die(mysql_error());

while($review_row = mysql_fetch_array($review_result)) {

$review_flag =1;

$review_title[] = $review_row['review_name'];

$reviewer_name[] = ucwords($review_row['review_reviewer_name']);

$review[] = $review_row['review_comment'];

$review_date[] = $review_row['review_date'];

$review_rating[] = generate_ratings($review_row['review_rating']);

}

$i = 0;

$review_details = '';

while ($i<sizeof($review)) {

$review_details .=<<<EOD

<tr>

<td width="15%" valign="top" align="center">$review_date[$i]</td>

<td width="15%" valign="top">$review_title[$i]</td>

<td width="10%" valign="top">$reviewer_name[$i]</td>

<td width="50%" valign="top">$review[$i]</td>

<td width="10%" valign="top" align="center">$review_rating[$i]</td>

</tr>

EOD;

$i++;

}

while ($row = mysql_fetch_array($movie_result)) {

$movie_name = $row['movie_name'];

$movie_director = $row['movie_director'];

$movie_leadactor = $row['movie_leadactor'];

$movie_year = $row['movie_year'];

$movie_run = $row['movie_run']." mins";

$movie_takings = $row['movie_takings'];

$movie_cost = $row['movie_cost'];

$rating=$row['rating'];

//get director's name from people table

get_director();

//get lead actor's name from people table

get_leadactor();

ratings

rating();

}

$movie_health = calculate_differences($movie_takings, $movie_cost);

$page_start =<<<EOD

<html>

<head>

<title>Details and Reviews for: $movie_name</title>

</head>

<body>

EOD;

$movie_details =<<<EOD

<table width="70%" border="0" cellspacing="2"

cellpadding="2" align="center">

<tr>

<th colspan="6"><u><h2>$movie_name: Details</h2></u></th>

</tr>

$movie_table_headings

<tr>

<td width="33%" align="center">$movie_name</td>

<td align="center">$movie_year</td>

<td align="center">$director</td>

<td align="center">$leadactor</td>

<td align="center">$movie_run</td>

<td>$movie_health</td>

<td>$rating</td>

</tr>

</table>

<br>

<br>

EOD;

if ($review_flag) {

$movie_details .=<<<EOD

<table width="95%" border="0" cellspacing="2"

cellpadding="20" align="center">

$review_table_headings

$review_details

</table>

EOD;

}

$page_end =<<<EOD

</body>

</html>

EOD;

$detailed_movie_info =<<<EOD

$page_start

$movie_details

$page_end

EOD;

echo $detailed_movie_info;

mysql_close();

function generate_ratings($review_rating) {

$movie_rating = '';

for($i=0; $i<$review_rating; $i++) {

$movie_rating .= "<img src=\"yes.jpeg\" width=14 > ";

}

return $movie_rating;

}

?>