Where Exist 子句的替代 MySQL

Question

我有这个 select 语句，在更大的数据集上运行需要相当长的时间

select lookup_svcscat_svcscatnew.SVCSCAT_NEW_DESC as svc_type, 
        enrolid, msclmid, dx1, dx2, dx3, 
        proc1,msk_cpt_mapping.surg_length_cd as SL_CD,
        msk_cpt_mapping.days as day_window,o.svcdate_form, pay,
        table_label
from ccaeo190_ky o
    left join lookup_svcscat_svcscatnew on o.svcscat = lookup_svcscat_svcscatnew.svcscat
    left join msk_cpt_mapping on o.proc1 = msk_cpt_mapping.cpt_code
where EXISTS 
        (
        select 1 
        from eoc_op_mapping e
        where e.msclmid = o.msclmid
            and e.enrolid = o.enrolid
            and proc1 =27447
        )
ORDER BY svcdate_form, msclmid;

我想 return 我的 ccaeo190_ky table 中满足 table eoc_op_mapping 上的 where EXISTS 子句要求的任何行。有什么方法可以使用连接或 select 语句来实现这些结果吗？

我在想：

select lookup_svcscat_svcscatnew.SVCSCAT_NEW_DESC as svc_type, 
        o.enrolid, o.msclmid, dx1, dx2, dx3, 
        proc1,msk_cpt_mapping.surg_length_cd as SL_CD,
        msk_cpt_mapping.days as day_window,o.svcdate_form, pay,
        table_label
from ccaeo190_ky o
    left join lookup_svcscat_svcscatnew on o.svcscat = lookup_svcscat_svcscatnew.svcscat
    left join msk_cpt_mapping on o.proc1 = msk_cpt_mapping.cpt_code
    inner join
        (select msclmid, SUM(IF(proc1 = 27447,1,0)) AS cpt 
        from eoc_op_mapping 
        group by enrolid
        HAVING cpt > 0) e 
on e.enrolid = o.enrolid
group by o.enrolid;

但不知道这个方向对不对

Answer 1

通常 EXISTS 比连接执行得更好。

如果您想尝试加入，这相当于您的 WHERE EXISTS:

.......................................................
inner join (
  select distinct msclmid, enrolid
  from eoc_op_mapping
  where proc1 = 27447
) e on e.msclmid = o.msclmid and e.enrolid = o.enrolid
.......................................................

如果 eoc_op_mapping 中没有重复的 msclmid, enrolid 组合，您可以删除 distinct。

Where Exist 子句的替代 MySQL

Alternative to Where Exist clause MySQL

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