Graphically displaying the average rating by taking data from database

Here we are collecting the rating and number of votes given by visitors from the two fields ( rating, nov ) of the table content_rating by using content id ( $cont_id) of the page. We will be displaying the average value of the ratings given, so we will divide total rating by number of votes. To give a better output we will format the result to two decimal places. You can change this formatting as per your requirement. Here is the code to display the average rating

if($stmt = $connection->prepare("SELECT rating,nov FROM content_rating WHERE content_rating.cont_id=?")){
  $stmt->bind_param('i',$cont_id);
  $stmt->execute();
  $result = $stmt->get_result();
  $row=$result->fetch_object();
  
}else{
  echo $connection->error;
}
if($result->num_rows>0){ // record exist for the page 
$score_avg=number_format(($row->rating/$row->nov),2,".","");
//($score/$nov);

echo "Average ratting:$score_avg : "; // display rating value

Displaying star images

After formatting we can display the value but we will try little more. We will display images in terms of number of stars showing the average rating the content got. For example we will display 2 full starts and 3 half stars to represent a rating of 2.34 within a scale of 1 to 5. We have two start images one showing full star and other showing half star. Here after rounding the average score to nearest integer we will be using one for loop to display full star images, then from that value of $i we will be displaying half star images till 5. Here is the code to do that .

$rt=round($score_avg);
// display the rating by start images. 
$img="";
$i=1;
while($i<=$rt){
$img=$img."<img src=images/star.gif >";
$i=$i+1;
}
while($i<=5){
$img=$img."<img src=images/star2.gif >";
$i=$i+1;
}
echo $img;

The above code can be modified to get formatted average value from MySQL table itself and there is no need to format in php side. You can read the details on MySQL data format here. The modified code is given here. Note that you can use any one of them for your displaying the ratings.

"SELECT format((rating/nov),0) as score_avg FROM content_rating WHERE content_rating.cont_id= $cont_id"

Full code is here. disp.php

<?Php
if($stmt = $connection->prepare("SELECT rating,nov FROM content_rating WHERE content_rating.cont_id=?")){
  $stmt->bind_param('i',$cont_id);
  $stmt->execute();
  $result = $stmt->get_result();
  $row=$result->fetch_object();
  
}else{
  echo $connection->error;
}
if($result->num_rows>0){ // record exist for the page 
$score_avg=number_format(($row->rating/$row->nov),2,".","");
//($score/$nov);

echo "Average ratting:$score_avg : "; // display rating value
$rt=round($score_avg);
// display the rating by star images. 
$img="";
$i=1;
while($i<=$rt){
$img=$img."<img src=images/star.gif >";
$i=$i+1;
}
while($i<=5){
$img=$img."<img src=images/star2.gif >";
$i=$i+1;
}
echo $img;
}
?>

That is the end of our rating script. We can add more features like flood interval, IP checking etc to the script.
Read the part I of Rating script

Scripts

Subhendu Mohapatra

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Displaying average rating

Displaying star images

Subhendu Mohapatra