INSERT INTO phpbb_posts_tmp (post_id,  
 IF (phpbb_posts.topic_id >= 5716, phpbb_posts.topic_id + 40, phpbb_posts.topic_id) AS topic_id,
 forum_id, poster_id, icon_id, poster_ip, post_time, post_reported, enable_bbcode, enable_smilies, enable_magic_url, enable_sig, post_username, post_subject, post_text, post_checksum, post_attachment, bbcode_bitfield, bbcode_uid, post_postcount, post_edit_time, post_edit_reason, post_edit_user, post_edit_count, post_edit_locked, post_visibility, post_delete_time, post_delete_reason, post_delete_user, post_modified, post_reputation, post_created)
FROM phpbb_posts ;

INSERT INTO phpbb_posts_tmp 
SELECT phpbb_posts.post_id, phpbb_posts.topic_id, phpbb_posts.forum_id, phpbb_posts.poster_id, phpbb_posts.icon_id, phpbb_posts.poster_ip, phpbb_posts.post_time, phpbb_posts.post_reported, phpbb_posts.enable_bbcode, phpbb_posts.enable_smilies, phpbb_posts.enable_magic_url, phpbb_posts.enable_sig, phpbb_posts.post_username, phpbb_posts.post_subject, 
If ( phpbb_posts.topic_id > 5715, phpbb_posts.topic_id + 40 , phpbb_posts.topic_id ) 
AS post_text, phpbb_posts.post_checksum, phpbb_posts.post_attachment, phpbb_posts.bbcode_bitfield, phpbb_posts.bbcode_uid, phpbb_posts.post_postcount, phpbb_posts.post_edit_time, phpbb_posts.post_edit_reason, phpbb_posts.post_edit_user, phpbb_posts.post_edit_count, phpbb_posts.post_edit_locked, phpbb_posts.post_visibility, phpbb_posts.post_delete_time, phpbb_posts.post_delete_reason, phpbb_posts.post_delete_user, phpbb_posts.post_modified, phpbb_posts.post_reputation, phpbb_posts.post_created
FROM phpbb_posts;