Important information
Blog B contains a few posts in the 'b2evolution Tips' category.
All these entries are designed to help you so, as EdB would say: "read them all before you start hacking away!" 
If you wish, you can delete these posts one by one after you have read them. You could also change their status to 'deprecated' in order to visually keep track of what you have already read.
MySQL error!
Table './b2evo/evo_comments' is marked as crashed and should be repaired(Errno=145)
Your query:SELECT comment_post_ID, comment_type, COUNT(*) AS type_count
FROM evo_comments
WHERE comment_post_ID IN (17,18,19,20,21)
GROUP BY comment_post_ID, comment_type