How is average star rating calculated in mysql?

How Not To Sort By Average Rating With Code Examples

Hello everyone, in this post we will look at how to solve the How Not To Sort By Average Rating problem in the programming language.

SELECT widget_id, ((positive + 1.9208) / (positive + negative) - 
                   1.96 * SQRT((positive * negative) / (positive + negative) + 0.9604) / 
                          (positive + negative)) / (1 + 3.8416 / (positive + negative)) 
       AS ci_lower_bound FROM widgets WHERE positive + negative > 0 
       ORDER BY ci_lower_bound DESC;

As we have seen, the How Not To Sort By Average Rating problem was solved by using a number of different instances.

How do you average a rating scale?

Average Rating Formula Each value is worth a different amount. For example, 4, 5-star ratings are worth 20 points, and 3, 3-star ratings are worth 9 points. Take all of these values, add them up to a total, then divide by the number of possible ratings (5). This results in the average rating.31-Oct-2021

How do you calculate Bayesian average?

True Bayesian estimate: weighted rating (WR) = (v ÷ (v+m)) × R + (m ÷ (v+m)) × C where: R = average for the mean = Rating. v = number of votes = votes.

What is a 5 point performance rating scale?

From goals to competencies. This is more often than not a 5 point rating scale (5– Outstanding, 4– Exceeds Expectations, 3- Meets Expectations, 2- Needs Improvement, 1- Unacceptable).26-Nov-2021

How is mean rating calculated?

You can find the mean, or average, of a data set in two simple steps: Find the sum of the values by adding them all up. Divide the sum by the number of values in the data set.09-Oct-2020

What is Bayesian model averaging?

Bayesian Model Averaging (BMA) is an application of Bayesian inference to the problems of model selection, combined estimation and prediction that produces a straightforward model choice criteria and less risky predictions.30-Sept-2015

How does Bayesian average work?

The Bayesian Average Bayesian Average computes the mean of a population by not only using the data residing in the population but also considering some outside information, like a pre-existing belief – a derived property from the dataset, for example, prior mean.

How is percentage rating calculated?

You can find your test score as a percentage by dividing your score by the total number of points, then multiplying by 100.

Which rating scale is best?

The four-point rating scale. Many organizations have used the standard three-point rating scale. However, in our research looking at the distribution of performance responses, we have found that a 4-point rating scale is often the best option to go for.

How do you justify your performance rating?

What to say in a performance review

• Talk about your achievements.
• Discuss ways to improve.
• Mention skills you've developed.
• Ask about company development.
• Provide feedback on tools and equipment.
• Ask questions about future expectations.
• Explain your experience in the workplace.
• Find out how you can help.

What is the most common type of rating scale?

What is a Rating Scale?

• This type of scale is one of the most commonly used questionnaire types for online as well as offline surveys.
• The most common example is the Likert scale, star rating, and slider.
• It is a popular choice for conducting market research.

by Vincy. Last modified on July 9th, 2022.

Star rating is used to rank pages, articles or posts published to the end user. This will help the user to identify and shortlist quality contents that are highly ranked. In this article, we are going to see how to create a PHP star rating system using jQuery AJAX.

This article is an improved version of the existing linked code. In this example, I have calculated the average star rating from the total ratings added for each tutorial.

This star rating example shows clickable five stars for each tutorial to add rating. The tutorials and their rating are stored in the database.

I have stored the rating based on the member session. I hardcoded the member session id at the first line of the program. You can integrate your authentication module to replace this by the logged in user session id.

This screenshot shows the star rating by highlighting the star icons. Also, it shows the average and the total ratings added for each tutorial in the database.

View Demo

List Tutorial with Star Rating

This code is used to retrieve the tutorial data from the database and to list them with the star rating. I combine the tables tutorials and tbl_member_rating using LEFT JOIN to get the star rating along with the tutorial information.

For each tutorial, I display the rating added by the user with the graphical representation of highlighting the stars. Also, I calculate the average rating out of 5 by using the overall rating added for the tutorial.

<?php
$member_id = 1;
require_once ("Rate.php");
$rate = new Rate();
$result = $rate->getAllPost();

if (! empty($result)) {
    $i = 0;
    foreach ($result as $tutorial) {
        $ratingResult = $rate->getRatingByTutorialForMember($tutorial["id"], $member_id);
        $ratingVal = "";
        if (! empty($ratingResult[0]["rating"])) {
            $ratingVal = $ratingResult[0]["rating"];
        }
        ?>
<tr>
                <td valign="top">
                    <div class="feed_title"><?php echo $tutorial["title"]; ?></div>
                    <div id="tutorial-<?php echo $tutorial["id"]; ?>"
                        class="star-rating-box">
                        <input type="hidden" name="rating" id="rating"
                            value="<?php echo $ratingVal; ?>" />
                        <ul
                            onMouseOut="resetRating(<?php echo $tutorial["id"]; ?>);">
  <?php
        for ($i = 1; $i <= 5; $i ++) {
            $selected = "";
            if (! empty($ratingResult[0]["rating"]) && $i <= $ratingResult[0]["rating"]) {
                $selected = "selected";
            }
            ?>
  <li class='<?php echo $selected; ?>'
                                onmouseover="highlightStar(this,<?php echo $tutorial["id"]; ?>);"
                                onmouseout="removeHighlight(<?php echo $tutorial["id"]; ?>);"
                                onClick="addRating(this,<?php echo $tutorial["id"]; ?>);">★</li>  
  <?php }  ?>
</ul>
                        <div
                            id="star-rating-count-<?php echo $tutorial["id"]; ?>"
                            class="star-rating-count">
                                <?php
        
        if (! empty($tutorial["rating_total"])) {
            $average = round(($tutorial["rating_total"] / $tutorial["rating_count"]), 1);
            echo "Average Star Rating is " . $average . " from the Total " . $tutorial["rating_count"] . " Ratings";
            ?>
                                
                                <?php } else { ?>
                                No Ratings
                                <?php  } ?>
                                </div>

                    </div>
                    <div><?php echo $tutorial["description"]; ?></div>
                </td>
            </tr>
<?php
    }
}
?>

Add Rating via jQuery AJAX

This jQuery code shows the functions used to handle the events triggered during the process of adding the star rating. For example, handling the hover effect to highlight and reset the star rating icons or handling the click event to add rating.

The function addRating() is called on selecting the star icon to rate a tutorial. This function will send a request to the PHP code for adding the star rating for a particular tutorial with the reference of the tutorial id.

<script src="jquery-3.2.1.min.js" type="text/javascript"></script>
<script>
	function highlightStar(obj, id) {
		removeHighlight(id);
		$('.demo-table #tutorial-' + id + ' li').each(function(index) {
			$(this).addClass('highlight');
			if (index == $('.demo-table #tutorial-' + id + ' li').index(obj)) {
				return false;
			}
		});
	}

	function removeHighlight(id) {
		$('.demo-table #tutorial-' + id + ' li').removeClass('selected');
		$('.demo-table #tutorial-' + id + ' li').removeClass('highlight');
	}

	function addRating(obj, id) {
		$('.demo-table #tutorial-' + id + ' li').each(function(index) {
			$(this).addClass('selected');
			$('#tutorial-' + id + ' #rating').val((index + 1));
			if (index == $('.demo-table #tutorial-' + id + ' li').index(obj)) {
				return false;
			}
		});
		$.ajax({
			url : "add_rating.php",
			data : 'id=' + id + '&rating='
					+ $('#tutorial-' + id + ' #rating').val(),
			type : "POST",
			success : function(data) {
				$("#star-rating-count-" + id).html(data);
			}
		});
	}

	function resetRating(id) {
		if ($('#tutorial-' + id + ' #rating').val() != 0) {
			$('.demo-table #tutorial-' + id + ' li').each(function(index) {
				$(this).addClass('selected');
				if ((index + 1) == $('#tutorial-' + id + ' #rating').val()) {
					return false;
				}
			});
		}
	}
</script>

PHP Code to Add / Update Star Rating

In PHP code it receives the rating data with the tutorial id. If the tutorial is rated already by the member, then the existing record will be updated with the new rating.

Otherwise, a new record will be added to the tbl_member_rating database table to store the user rating. The code for firing the insert or update on the rating database is,

<?php
$member_id = 1;
if (! empty($_POST["rating"]) && ! empty($_POST["id"])) {
    require_once ("Rate.php");
    $rate = new Rate();
    
    $ratingResult = $rate->getRatingByTutorial($_POST["id"], $member_id);
    
    if (! empty($ratingResult)) {
        $rate->updateRating($_POST["rating"], $ratingResult[0]["id"]);
    } else {
        $rate->addRating($_POST["id"], $_POST["rating"], $member_id);
    }
    
    $postRating = $rate->getRatingByTutorial($_POST["id"]);
    
    if (! empty($postRating[0]["rating_total"])) {
        $average = round(($postRating[0]["rating_total"] / $postRating[0]["rating_count"]), 1);
        echo "Average Star Rating is " . $average . " from the Total " . $postRating[0]["rating_count"] . " Ratings";
    } else {
        echo "No Ratings";
    }
}
?>

View DemoDownload

↑ Back to Top

How are average star ratings calculated?

How do you calculate average rating in SQL?

How is average calculated in MySQL?

How do you calculate average rating in PHP?