select a.id,a.plan_num,a.material_code,a.material_desc,a.unit,a.con_num,a.send_place,a.ccz,a.contract_num,a.dcplan_sh,a.plan_sendrq,a.Shipper,a.Shipper_tel,a.dalei,d.isDirect,d.region,e.supplier_namefromdelivery_plan aleft join (select order_num,order_row_num,supplier_name from material_china_order where document_date>='2022-01-01' and document_date<='2022-12-31') eon a.pzbh=e.order_numand a.pzhxm=e.order_row_numleft join ( select purchase_order_num,purchase_order_line_item_code,isDirect,region from material_china_plan where submission_date>='2022-01-01' and submission_date<='2022-12-31') don a.pzbh=d.purchase_order_numand a.pzhxm=d.purchase_order_line_item_codeleft join delivery_power b on a.dalei=b.qxand a.zt='2'and a.ccz='xxx' and b.czz='xxx' and b.code='80598231' order by plan_sendrq desc如题,d和e中数据较多,现有一个这样的sql ,如何增加索引可以提升数据查询速度