从列sql获得平均值

Question

我有一个SQL查询，并想知道如何实现一个总和来计算平均值。

我创建了此查询以输出以下图片：

SELECT d.date, CONCAT_WS(' ', p.PatientFname ,p.PatientLname) AS "Patient", dc.drugcost_cost, pc.pharmacy_name FROM drugcost dc JOIN patients_copy p ON dc.Patients_copy_idPatients = p.idPatients LEFT JOIN time d ON dc.time_idtime = d.idtime LEFT JOIN pharmacy_location pc ON dc.pharmacy_location_idpharmacy = pc.idpharmacy ORDER BY Patient ASC 

我想扩展查询以获取新列或新查询中同一患者的每年平均值。

这可能吗？我希望你明白我想要的东西。

由于

Answer 1

SELECT EXTRACT(YEAR FROM date) AS "Year",
       CONCAT_WS(' ', p.PatientFname ,p.PatientLname) AS "Patient", 
       AVG(dc.drugcost_cost) AS "AvgCost"
FROM drugcost dc 
     JOIN patients_copy p ON dc.Patients_copy_idPatients = p.idPatients 
     LEFT JOIN time d ON dc.time_idtime = d.idtime 
     LEFT JOIN pharmacy_location pc ON dc.pharmacy_location_idpharmacy = pc.idpharmacy 
GROUP BY EXTRACT(YEAR FROM date),
         ONCAT_WS(' ', p.PatientFname ,p.PatientLname)

将pc.pharmacy_name添加到结果中：

SELECT EXTRACT(YEAR FROM date) AS "Year",
       CONCAT_WS(' ', p.PatientFname ,p.PatientLname) AS "Patient", 
       AVG(dc.drugcost_cost) AS "AvgCost",
       pc.pharmacy_name
FROM drugcost dc 
     JOIN patients_copy p ON dc.Patients_copy_idPatients = p.idPatients 
     LEFT JOIN time d ON dc.time_idtime = d.idtime 
     LEFT JOIN pharmacy_location pc ON dc.pharmacy_location_idpharmacy = pc.idpharmacy 
GROUP BY EXTRACT(YEAR FROM date),
         ONCAT_WS(' ', p.PatientFname ,p.PatientLname),
         pc.pharmacy_name

Answer 2

AVG() SQL函数可以帮助你

SELECT d.date, CONCAT_WS(' ', p.PatientFname ,p.PatientLname) AS "Patient",  
       AVG(dc.drugcost_cost) AS "Average", pc.pharmacy_name 
FROM drugcost dc 
JOIN patients_copy p 
  ON dc.Patients_copy_idPatients = p.idPatients 
LEFT JOIN time d 
  ON dc.time_idtime = d.idtime 
LEFT JOIN pharmacy_location pc 
  ON dc.pharmacy_location_idpharmacy = pc.idpharmacy 
ORDER BY Patient ASC 

SELECT d.date, CONCAT_WS(' ', p.PatientFname ,p.PatientLname) AS "Patient",  
       AVG(dc.drugcost_cost) AS "Average", pc.pharmacy_name 
FROM drugcost dc 
JOIN patients_copy p 
  ON dc.Patients_copy_idPatients = p.idPatients 
LEFT JOIN time d 
  ON dc.time_idtime = d.idtime 
LEFT JOIN pharmacy_location pc 
  ON dc.pharmacy_location_idpharmacy = pc.idpharmacy 
GROUP BY "Patient"
ORDER BY Patient ASC