Q&A for professionals, academics, and students working within the systems development life cycle
WITH TotalPosts AS ( SELECT COUNT(*) AS TotalPostCount FROM Posts ), PostsWithComments AS ( SELECT COUNT(DISTINCT PostId) AS PostsWithCommentCount FROM Comments WHERE PostId IS NOT NULL ) SELECT (TotalPosts.TotalPostCount - PostsWithComments.PostsWithCommentCount) * 100.0 / TotalPosts.TotalPostCount AS PercentageNoComments FROM TotalPosts, PostsWithComments;