instruction: Posts whose titles are prefixed with one of its tags. Posts whose titles are of the form 'Tag: Blah blah blah', where 'Tag' is already one of the tags on that post.
response: SELECT Id AS "post_link", Title FROM Posts WHERE Title LIKE '%:%' AND LEFT(Title, STR_POSITION(Title, ':') - 1) IN (SELECT Tags.TagName FROM PostTags INNER JOIN Tags ON PostTags.TagId = Tags.Id WHERE PostTags.PostId = Posts.Id) ORDER BY CreationDate DESC