聚合函数或GROUP BY子句 [英] Either an aggregate function or the GROUP BY clause

问题描述

我使用了以下查询:

select Patients.LastName, 
  avg (PatientVisits.Pulse)as pulse,
  avg (patientvisits.depressionlevel)as depressionLevel  
from Patients 
left join PatientVisits 
   on Patients.PatientKey=PatientVisits.PatientKey

但是出现以下错误:

消息8120(级别16，状态1，行1)在选择列表中的"Patients.LastName"列无效，因为它既不包含在聚合函数中也不在GROUP BY子句中.

Msg 8120, Level 16, State 1, Line 1 Column 'Patients.LastName' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

推荐答案

您需要在查询中添加GROUP BY:

select Patients.LastName, 
   avg (PatientVisits.Pulse)as pulse,
   avg (patientvisits.depressionlevel)as depressionLevel  
from Patients 
left join PatientVisits 
  on Patients.PatientKey=PatientVisits.PatientKey 
GROUP BY Patients.LastName

SQL Server要求SELECT列表中未包含在聚合函数中的所有列都包含在GROUP BY中.由于要在汇总数据时尝试返回Patients.LastName，因此必须将该列包括在分组依据中.

SQL Server requires any columns in your SELECT list that are not in an aggregate function be included in a GROUP BY. Since you are trying to return the Patients.LastName while you are aggregating the data you must include that column in a group by.

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