Body
              Diese Befehle löschen die Inhalte aus den Tabellen field_data_comment_body und field_data_revision_comment_body, deshalb leg vorher eine Sicherungskopie an!
DELETE t1.*
FROM field_data_comment_body t1
    LEFT JOIN comment t2 ON t1.entity_id = t2.cid
WHERE t2.cid IS NULL
DELETE t1.*
FROM field_revision_comment_body t1
    LEFT JOIN comment t2 ON t1.entity_id = t2.cid
WHERE t2.cid IS NULL
OPTIMIZE TABLE `field_data_comment_body` ,
`field_revision_comment_body`