如何对一对多关系中的特定记录进行计数/分类？

您可以使用子查询或 CTE 作为帮助程序。结婚

select ChargeType, count(*)
from (
   Select case 
      when exists (select * from Charges ch 
                   where ch.CourtId = c.CourtId and ch.Class in ('A','B', 'C')) 
      then 'Misdemeanors' else 'Felony' end as ChargeType
from Courts c
) tmp
group by ChargeType;

编辑：

WITH tmp AS (SELECT CountyID, CASE WHEN EXISTS 
  (SELECT *
   FROM PendingCharge AS pc
   WHERE c.ID=pc.CourtID AND pc.Class IN ('M', 'X', '1', '2', '3', '4')) 
      THEN 'Felony' 
      ELSE 'Misdemeanor' 
   END AS ChargeType
   FROM Court AS c)
SELECT CountyID, 
  SUM(CASE WHEN ChargeType='Felony' THEN 1 ELSE 0 END) AS [Number Felony], 
  SUM(CASE WHEN ChargeType='Misdemeanor' THEN 1 ELSE 0 END) AS [Number Misdemeanor]
FROM tmp
GROUP BY CountyID;

这是 DBFiddle 演示。