ORA-00937：不是单组组功能，计数功能

 select  officer.forename || ' ' || Officer.surname || ' is working on : ' || 
 count(crime.crime_id)  "Officers Current Crimes"

 From officer, crime
 where officer.officer_id = crime.officer_id
 order by crime.crime_id;
 select  officer.forename || ' ' || Officer.sur