在使用左，右，或者內連線的時候，在需要使用排序的時候，不妨先以乙個表為標準，先進行排序，這樣可以提供語句的效能
比如:優化前:
select *
from (select a.*, row_number() over(order by createdate desc) row_num
from (select a.id as id,
a.code as code,
a.last_store_job_id as laststorejobid,
a.job_date as jobdate,
a.job_store_id as jobstoreid,
c.name as jobstorename,
a.transfer_store_id as transferstoreid,
d.name as transferstorename,
a.store_company_id as storecompanyid,
e.company_fullname as companyname,
a.extract_company_id as extractcompanyid,
f.company_fullname as extractcompanyname,
a.source_type as sourcetype,
a.external_code as externalcode,
a.remark as remark,
a.allot_type as allottype,
a.allot_status as allotstatus,
a.status as status,
a.pda_status as pdastatus,
a.job_type_id as jobtypeid,
a.action_type_id as actiontypeid,
a.solve_status as solvestatus,
a.update_date as updatedate,
a.create_date as createdate,
a.vehicle_code as vehiclecode,
a.user_id as userid,
g.user_name as username,
a.flow_status as flowstatus,
a.target_allocation_id as targetallocationid,
h.name as allocationname,
(select count(*)
from store_job_flow_nodes i
left join store_job_flow_modes j
on j.id = i.job_flow_mode_id
and i.action_type_id = 'hwman02'
left join store_job_flows k
on k.job_flow_mode_id = j.id
where k.store_job_id = a.id) as nextisplan
from [size=x-large][color=red]store_jobs a[/color][/size] left join store_jobs b
on a.last_store_job_id = b.id
left join stores c
on a.job_store_id = c.id
left join stores d
on a.transfer_store_id = d.id
left join companys e
on a.store_company_id = e.id
left join companys f
on a.extract_company_id = f.id
left join users g
on a.user_id = g.id
left join allocations h
on a.target_allocation_id = h.id
where 1 = 1
and a.action_type_id = 'hwman01'
and a.job_date between
to_date('2014-07-02 00:00:00', 'yyyy-mm-dd hh24:mi:ss') and
to_date('2014-08-02 23:59:59', 'yyyy-mm-dd hh24:mi:ss')
and a.job_type_id = 'hwmsn02'
[size=x-large][color=red] order by a.create_date desc [/color][/size]) a
)where row_num between 1 and 30
order by createdate desc
優化後:
select *
from (select a.*, row_number() over(order by createdate desc) row_num
from (select a.id as id,
a.code as code,
a.last_store_job_id as laststorejobid,
a.job_date as jobdate,
a.job_store_id as jobstoreid,
c.name as jobstorename,
a.transfer_store_id as transferstoreid,
d.name as transferstorename,
a.store_company_id as storecompanyid,
e.company_fullname as companyname,
a.extract_company_id as extractcompanyid,
f.company_fullname as extractcompanyname,
a.source_type as sourcetype,
a.external_code as externalcode,
a.remark as remark,
a.allot_type as allottype,
a.allot_status as allotstatus,
a.status as status,
a.pda_status as pdastatus,
a.job_type_id as jobtypeid,
a.action_type_id as actiontypeid,
a.solve_status as solvestatus,
a.update_date as updatedate,
a.create_date as createdate,
a.vehicle_code as vehiclecode,
a.user_id as userid,
g.user_name as username,
a.flow_status as flowstatus,
a.target_allocation_id as targetallocationid,
h.name as allocationname,
(select count(*)
from store_job_flow_nodes i
left join store_job_flow_modes j
on j.id = i.job_flow_mode_id
and i.action_type_id = 'hwman02'
left join store_job_flows k
on k.job_flow_mode_id = j.id
where k.store_job_id = a.id) as nextisplan
from [size=x-large][color=blue](select * from store_jobs order by create_date desc) a[/color][/size] left join store_jobs b
on a.last_store_job_id = b.id
left join stores c
on a.job_store_id = c.id
left join stores d
on a.transfer_store_id = d.id
left join companys e
on a.store_company_id = e.id
left join companys f
on a.extract_company_id = f.id
left join users g
on a.user_id = g.id
left join allocations h
on a.target_allocation_id = h.id
where 1 = 1
and a.action_type_id = 'hwman01'
and a.job_date between
to_date('2014-07-02 00:00:00', 'yyyy-mm-dd hh24:mi:ss') and
to_date('2014-08-02 23:59:59', 'yyyy-mm-dd hh24:mi:ss')
and a.job_type_id = 'hwmsn02') a)
where row_num between 1 and 30
order by createdate desc
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