เลือก AVG(CAST(Reputation AS FLOAT)) จาก Users;.ไม่จำเป็นต้องใช้ตารางทั้งหมด
SELECT AVG(CAST(Reputation AS FLOAT)) FROM Users;.It is not neccessary to use all the tables.
 PostFeedback:  Id [ number]  PostId [ number]  IsAnonymous [ boolean]  VoteTypeId [ number]  CreationDate [ time] 
SELECT AVG(CAST(Reputation AS FLOAT)) FROM Users