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I am doing a special migration from someone's custom CMS to a WP installation. I successfully got the posts and comments migrated into their respective tables. Now I need to get the comment count into the wp_posts table for each matching id. I have something like this. I'm close, I think:

SELECT COUNT(comment_content) AS total_comments, comment_post_ID AS commentID
FROM wp_comments
GROUP BY comment_post_ID;
--mysql won't let me run the group by on just the returned count column, so I'm stuck with    two columns of data when I just want to insert one

UPDATE wp_posts SET comment_count = total_comments WHERE wp_posts.ID = commentID;
--So I tried to set my returned data to variables and assign them into the update statement..which doesn't work

Anyway, perhaps I need to iterate all the posts, find a matching ID and update it by moving the cursor? Or is there an easier way i'm missing somehow?

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The easy way is to just write PHP to go through all the posts and call wp_update_comment_count() on each post ID.

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But let's say I really wanted to figure this out with MySQL. Any idea how? – Lynn Nov 30 '12 at 22:11
up vote 0 down vote accepted

And I finally figured it out. For those who want to know how something like this is handled with MySQL, here it is:

    UPDATE wp_posts, (SELECT COUNT(comment_content) AS total_comments, comment_post_ID
FROM wp_comments
GROUP BY comment_post_ID) x
       SET wp_posts.comment_count = x.total_comments
       WHERE wp_posts.ID = x.comment_post_ID;
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That doesn't account for deleted or spam comments. You need to only count comments with comment_approved = '1'. – Otto Dec 9 '12 at 19:47
Good point. Though I was doing this from a custom built CMS. So the comments either existed or didn't. No spam or deleted status. – Lynn Dec 11 '12 at 21:56

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