mysql - 获取第一个匹配条件的结果，不考虑下一个匹配条件的结果

Question

我需要从第一个匹配条件获取结果，如果在该级别找到结果，则从那里返回或转到下一个级别 找到结果。

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Answer 1

这是一个优先级查询(有联系)。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;