替代 Where Exist 子句 MySQL

Question

我有这个 select 语句需要很长时间才能在更大的数据集上运行

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;

我想返回我的 ccaeo190_ky 表中满足表 eoc_op_mapping 的 where EXISTS 子句要求的任何行。有没有办法使用连接或选择语句来实现这些结果？

我在想这样的事情：

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;

但我不知道这是否是正确的方向

Answer 1

通常EXISTS 的性能优于连接。

如果你想尝试加入，这相当于你的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。