Question

我有一份报告，其中包含3个子报告和几个要在每个报告中进行优化的查询。第一个在WHERE分支中有几个OR子句，OR正在通过IN选项进行过滤，这些选项会拉动子查询。

我这主要是从阅读this SO post来说。特别是LBushkin的第二点。

我不是TSQL的最佳人选，但我知道这个效率非常低。我想我需要做两件事。

我知道我需要为所涉及的表添加索引。
我认为可以大大增强查询。

所以我的第一步似乎是改进查询。从那里我可以看看涉及哪些列和表，从而确定索引。

此时我还没有发布表格模式，因为我正在寻找更多选项/注意事项，例如使用cte替换所有IN子查询。

如果需要，我一定会发布任何有用的内容，例如物理读取等。

SELECT DISTINCT 
  auth.icm_authorizationid, 
  auth.icm_documentnumber
FROM 
  Filteredicm_servicecost AS servicecost 

INNER JOIN Filteredicm_authorization AS auth ON 
auth.icm_authorizationid = servicecost.icm_authorizationid 

INNER JOIN Filteredicm_service AS service ON 
service.icm_serviceid = servicecost.icm_serviceid 

INNER JOIN Filteredicm_case AS cases ON 
service.icm_caseid = cases.icm_caseid

WHERE
  (cases.icm_caseid IN
    (SELECT icm_caseid FROM Filteredicm_case AS CRMAF_Filteredicm_case)) 

  OR (service.icm_serviceid IN
    (SELECT icm_serviceid FROM Filteredicm_service AS CRMAF_Filteredicm_service)) 

  OR (servicecost.icm_servicecostid IN
    (SELECT icm_servicecostid FROM Filteredicm_servicecost AS CRMAF_Filteredicm_servicecost)) 

  OR (auth.icm_authorizationid IN
    (SELECT icm_authorizationid FROM Filteredicm_authorization AS CRMAF_Filteredicm_authorization))

Answer 1

EXISTS通常比IN快得多，因为查询引擎能够更好地优化它。

试试这个：

WHERE EXISTS (SELECT 1 FROM FROM Filteredicm_case WHERE icm_caseid = cases.icm_caseid)
    OR EXISTS (SELECT 1 FROM Filteredicm_service WHERE icm_serviceid = service.icm_serviceid)
    OR EXISTS (SELECT 1 FROM Filteredicm_servicecost WHERE icm_servicecostid = servicecost.icm_servicecostid)
    OR EXISTS (SELECT 1 FROM Filteredicm_authorization WHERE icm_authorizationid = auth.icm_authorizationid)

此外，Filteredicm_case.icm_caseid上的索引，Filteredicm_service.icm_serviceid上的索引，Filteredicm_servicecost.icm_servicecostid上的索引以及Filteredicm_authorization.icm_authorizationid上的索引将提高此查询的效果。但是，它们看起来应该是键，所以我怀疑索引已经存在。

但是，除非我误读，否则此WHERE条款无法评估除真实以外的其他任何内容。

您撰写的条款WHERE cases.icm_caseid IN (SELECT icm_caseid FROM Filteredicm_case AS CRMAF_Filteredicm_case)。但是，cases是Filteredicm_case的别名。这相当于WHERE Filteredicm_case.icm_caseid IN (SELECT icm_caseid FROM Filteredicm_case AS CRMAF_Filteredicm_case)。只要Filteredicm_case.icm_caseid不是NULL，就属实。

WHERE子句中的其余部分存在相同的逻辑错误：

(service.icm_serviceid IN (SELECT icm_serviceid FROM Filteredicm_service AS CRMAF_Filteredicm_service))

service是Filteredicm_service的别名。只要icm_serviceid不为空

，这始终为真

(servicecost.icm_servicecostid IN (SELECT icm_servicecostid FROM Filteredicm_servicecost AS CRMAF_Filteredicm_servicecost))

servicecost是Filteredicm_servicecost的别名。只要icm_servicecostid不为空，就始终为真。

(auth.icm_authorizationid IN (SELECT icm_authorizationid FROM Filteredicm_authorization AS CRMAF_Filteredicm_authorization))

auth是Filteredicm_authorization的别名。只要icm_authorizationid不为空，就始终为真。

我不明白你想要完成的事情。

慢速运行BIDS报告查询...使用IN子查询在WHERE分支中使用OR子句

1 个答案: