这是一个优先级排序查询（有关系）。一种方法使用 dense_rank() :

select rsc.* 
from (select rsc.*,
             dense_rank() over (order by case when rsc.entityId = :accountId and rsc.entityTypeCode = 'A' then 1
                                              when rsc.entityId = :companyId and rsc.entityTypeCode = 'C' then 2
                                              when rsc.entityId = :issuerId and rsc.entityTypeCode = 'I' then 3
                                              else 4
                                         end) as seqnum
      from CurrentRuleSetContents rsc 
      where (rsc.entityId = :accountId and rsc.entityTypeCode = 'A') or
            (rsc.entityId = :companyId and rsc.entityTypeCode = 'C') or 
            (rsc.entityId = :issuerId and rsc.entityTypeCode = 'I') or 
            (rsc.industryCode = :industryCode)
    ) rsc
where seqnum = 1;