s.ไม่จำเป็นที่จะต้องใช้ทุกตาราง
s.It is not neccessary to use all the tables.
 PostFeedback:  Id [ number]  PostId [ number]  IsAnonymous [ boolean]  VoteTypeId [ number]  CreationDate [ time] 
SELECT COUNT('Id') FROM Posts WHERE Posts.Tags = 'Ruby'