This is the comment_meta from wordpress. In there is a custom meta_key: rating.
I would like to get the SUM of all the ratings for that individual post.
The point being of this is to get the average from the user ratings. I have the total number of commenters, I just need the SUM.
The use of it is for the Schema.org AggregateReview: <meta itemprop="ratingValue" content=""/>.
I have tried to add the value via jQuery, but for some reason the schema isn’t registering the text added later in the DOM.
var sum = 0;
$('.comment_rate').each(function(){
numItems = $('.comment_rate').length
sum += (parseFloat($(this).text()) / numItems);
$('span[itemprop="ratingValue"]').text(sum);
});
ORIGINAL POST
I have this table (sorry, image is only way I know how to show):
I would like to sum the meta_value from the matching comment_id.
So far I have this but it SUMs the entire column not the ones matching the same id.
<?php
$result = mysql_query('SELECT SUM(meta_value) AS value_sum FROM wp_play_commentmeta');
$row = mysql_fetch_assoc($result);
$sum = $row['value_sum'];
echo $sum;
?>
Use a GROUP BY:
SELECT comment_id, SUM(meta_value) AS value_sum
FROM wp_play_commentmeta
GROUP BY comment_id;
See it in action here:
If you want to do this for only those that had rating metakey, then add that in the WHERE clause. Something like this:
SELECT comment_id, SUM(meta_value) AS value_sum
FROM wp_play_commentmeta
wHERE meta_key = 'rating'
GROUP BY comment_id;
Update:
JOIN the two tables, and GROUP BY post_id. Something like this:
SELECT
p.post_id,
SUM(m.meta_value) AS value_sum
FROM wp_play_commentmeta AS m
INNER JOIN wp_play_comments AS p ON m.comment_ID = p.comment_Id
wHERE meta_key = 'rating'
GROUP BY p.post_id;
Note that: Please stop using Mysql_* extensions, they are deprecated. Furtheremore your code this way is vulnerable to SQL Injection. Use PDO or prepared statements instead.
Answer：
query will be
SELECT SUM(meta_value) AS value_sum, comment_id FROM wp_play_commentmeta
Group by comment_id
