sql优化-总结
1、尽量缩小数据范围。
2、能一个sql解决的，坚决不用两条sql。利用case when或decode。
select month_id,
corppkno,
sum(exportSum_new) exportSum_new,
sum(exportSum_newLy) exportSum_newLy,
sum(exportSum_Support) exportSum_Support,
sum(exportSum_SupportLy) exportSum_SupportLy
from ( /*当年累计出口*/
select a.month_id,
c.corppkno,
decode(a.isnewinsurant, null, 0, b.exportdollar) exportSum_new,/*此处为了用一条sql实现*/
0 exportSum_newLy,
b.exportdollar exportSum_Support,
0 exportSum_SupportLy
from (select trunc(t1.month_id / 100) yearid,
t1.month_id,
t3.cocode,
max(t.newinsurantpkno_sm) isnewinsurant /*当月新增的客户*/
from stdw.F_Sum_SupportInsurant_SM t,
stdw.lu_month_cumulate t1,
stdw.d_t_customer t2,
stdw.d_t_Customsenterprisemapping t3
where t.monthid = t1.month_cumul_id
and t.supportinsuantpkno_sm = t2.pkno
and t2.crmno = t3.customno
and t3.state = '1'
and t1.month_id <= to_char(sysdate - 1, 'YYYYMM')
group by t1.month_id, t3.cocode) A,
stdw.f_custom_company_composite B,
stdw.d_custom_branch_province C,
stdw.lu_month_cumulate D /*此sql先用子查询A限定范围，再通过A去关联B。因为B的范围大，如果对B进行汇总后再和A关联，效率较低*/
where b.monthid = d.month_cumul_id
and b.corpid = c.corpid
and a.yearid = b.yearid /*跨区访问*/
and a.month_id = d.month_id
and a.cocode = b.cocode
union all
/*上年总出口额*/
select a.month_id,
b.corppkno,
0 exportSum_new,
decode(a.isnewinsurant, null, 0, b.exportdollar) exportSum_newLy,
0 exportSum_Support,
b.exportdollar exportSum_SupportLy
from (select trunc(t1.month_id / 100) - 1 yearid_ly,
t1.month_id,
t3.cocode,
max(t.newinsurantpkno_sm) isnewinsurant /*当月新增的客户*/
from stdw.F_Sum_SupportInsurant_SM t,
stdw.lu_month_cumulate t1,
stdw.d_t_customer t2,
stdw.d_t_Customsenterprisemapping t3
where t.monthid = t1.month_cumul_id
and t.supportinsuantpkno_sm = t2.pkno
and t2.crmno = t3.customno
and t3.state = '1'
and t1.month_id <= to_char(sysdate - 1, 'YYYYMM')
group by t1.month_id, t3.cocode) A,
(select t1.outputyear yearid,
t1.cocode,
t4.corppkno,
t1.totaldollar exportdollar
from stdw.f_custom_company_total t1,
stdw.d_custom_company t2,
stdw.d_custom_province_zone t3,
stdw.d_custom_branch_province t4
where t1.cocode = t2.cocode
and t2.zonecode = t3.zone
and t3.province_no = t4.proviceid) B
where a.yearid_ly = B.yearid
and a.cocode = B.cocode)
group by month_id, corppkno