instruction: Posts with [ibm] that don't have any product-specific tags.
response: SELECT p.Id AS "post_link", p.CreationDate AS "creation_date", p.Tags FROM Posts AS p LEFT JOIN PostTags AS pt ON p.Id = pt.PostId LEFT JOIN Tags AS t ON pt.TagId = t.Id WHERE t.TagName = 'ibm' AND NOT EXISTS(SELECT t2.Id FROM PostTags AS pt2 LEFT JOIN Tags AS t2 ON pt2.TagId = t2.Id WHERE p.Id = pt2.PostId AND t2.TagName IN ('clearcase', 'dxl', 'ibm-bpm', 'ibm-midrange', 'rad', 'rational', 'rational-rose', 'websphere', 'websphere-mq', 'worklight'))