จำนวนผู้เชี่ยวชาญที่กระตือรือร้นต่อสัปดาห์ ไม่จำเป็นต้องใช้ตารางทั้งหมด
Number of active experts per week.It is not neccessary to use all the tables.
 PostTypes:  Id [ number]  Name [ text] 
SELECT YR_WK, COUNT(*) AS NumActiveExperts FROM (SELECT (TIME_TO_STR(p.CreationDate, '%y') + (TIME_TO_STR(p.CreationDate, '%W') - 1) / 52.0) AS YR_WK, u.Id AS UID, COUNT(*) AS NumAnswers FROM Users AS u INNER JOIN Posts AS p ON p.OwnerUserId = u.Id AND p.PostTypeId = 2 AND p.Score > 0 GROUP BY (TIME_TO_STR(p.CreationDate, '%y') + (TIME_TO_STR(p.CreationDate, '%W') - 1) / 52.0), u.Id) AS AnsPerUPerWk WHERE NumAnswers > 1 GROUP BY YR_WK ORDER BY YR_WK