การทดสอบสามรายการที่ทำบ่อยที่สุดนับตั้งแต่ 6 ปีที่แล้วสำหรับผู้ป่วยอายุ 20 ปีคืออะไร? ไม่จำเป็นต้องใช้ตารางทั้งหมด
what was the three most frequently taken test since 6 years ago for patients with age 20s?It is not neccessary to use all the tables.
 labevents:  row_id [ number]  subject_id [ number]  hadm_id [ number]  itemid [ number]  charttime [ time]  valuenum [ number]  valueuom [ text] 
SELECT d_labitems.label FROM d_labitems WHERE d_labitems.itemid IN (SELECT t1.itemid FROM (SELECT labevents.itemid, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.age BETWEEN 20 AND 29) AND DATETIME(labevents.charttime) >= DATETIME(CURRENT_TIME(), '-6 year') GROUP BY labevents.itemid) AS t1 WHERE t1.c1 <= 3)