Sql 这个查询需要很多时间来执行,如何优化它?
我用它来清理田野。但执行起来要花上几个小时Sql 这个查询需要很多时间来执行,如何优化它?,sql,database,replace,database-performance,query-performance,Sql,Database,Replace,Database Performance,Query Performance,我用它来清理田野。但执行起来要花上几个小时 select c.* from ( select distinct a.*, b.* from ( --Table 1 select replace(replace(replace(replace(AGENCY_NAME,'',''),'',''),'/',''),'\\','') as agency_name, LEN(replace(replace(replace(replace(AGENCY_NAME,
select c.*
from
(
select distinct a.*, b.*
from
(
--Table 1
select replace(replace(replace(replace(AGENCY_NAME,'',''),'',''),'/',''),'\\','')
as agency_name,
LEN(replace(replace(replace(replace(AGENCY_NAME,' ',''),'-',''),'/',''),'\\',''))
as agency_len
from dbo.tbl_stars_agency
where replace(replace(replace(replace(AGENCY_NAME,' ',''),'-',''),'/',''),'\\','')
not in ('')
) a
inner join
(
--Table 2
select replace(replace(replace(replace(RESPONDENT_NAME_PER,' ',''),'.',''),'/',''),'\\','')
as respondent_name,
len(replace(replace(replace(replace(RESPONDENT_NAME_PER,' ',''),'-',''),'/',''),'\\',''))
as respondent_len
from dbo.TBL_cacs_ecb
where replace(replace(replace(replace(RESPONDENT_NAME_PER,' ',''),'-',''),'/',''),'\\','') not in ('')
) b
on substring(a.agency_name,1,15)=SUBSTRING(b.respondent_name,1,15)
) c
inner join
(
--Table 3
select replace(replace(replace(replace(NM_ENTITY,' ',''),'-',''),'/',''),'\\','')
as nm_entity,
LEN(replace(replace(replace(replace(NM_ENTITY,' ',''),'-',''),'/',''),'\\',''))
as nm_entity_len
from dbo.RMFS010_TF1NAME
where replace(replace(replace(replace(NM_ENTITY,' ',''),'-',''),'/',''),'\\','')
not in ('')
) d
on substring(c.agency_name,1,5)=substring(d.nm_entity,1,5) or
substring(c.respondent_name,1,5)=substring(d.nm_entity,1,5)
我想根据表中的name字段比较这三个表。我已经计算了长度,并使用子字符串函数来匹配多达15个位置。一种方法是添加计算列并为它们编制索引:
ALTER TABLE dbo.tbl_stars_agency
ADD agency_len AS LEN(replace(replace(replace(
replace(AGENCY_NAME,' ',''),'-',''),'/',''),'\',''))
PERSISTED;
现在添加一个索引:
CREATE INDEX MyIndex dbo.tbl_stars_agency
(agency_len);
现在,这方面的任何搜索都应该快得多
您可以更改此行:
where replace(replace(replace(
replace(AGENCY_NAME,' ',''),'-',''),'/',''),'\','')
not in ('')
为此:
where agency_len = 0
尝试一下,如果有帮助的话,我们可以考虑对其他专栏进行此操作
PS:你需要确保你的表达式是无懈可击的,不会因长度无效等原因崩溃。否则它将停止你插入和更新记录请用谷歌重新堆叠溢出问题标记,然后使用代码块格式(单击“{}”),并查看你的帖子在编辑窗口下的显示方式。同时阅读和阅读。另外,请阅读DBMS和用户查询优化。请格式化您的代码。乍一看,由于您正在动态清理数据,因此在这种情况下添加索引可能不会有多大帮助。希望现在它更容易理解。您应该在查询数据之前清理数据。应用这样的函数将消除您使用索引的能力。如果您有能力更改表,您可以创建一些计算的持久化列,然后在这些列上放置索引,然后在索引列上进行联接。每个表有多少行?请编辑您的问题并添加此信息