PL / SQL comments in order to enhance the readability (illustration)

In order to increase the readability of the code, be sure to comment, this is too important; otherwise behind himself wrote
nothing do not understand

 /*
  Ifsapp.PROD_STRUCTURE :BOM产品结构表
  Ifsapp.shop_material_alloc：车间订单的物料清单表
  Ifsapp.shop_ord：车间订单
  实现了BOM产品结构表和车间订单物料清单表和车间订单关联
  */ 
--Harry
    select b.part_no,b.line_item_no,floor(a.line_item_no)                             
    from Ifsapp.PROD_STRUCTURE b,Ifsapp.shop_material_alloc a,Ifsapp.shop_ord c
    where c.part_no=b.part_no and b.contract=c.contract                                    
    and b.alternative_no= IFSAPP.shop_ord_api.Get_Structure_Alternative(a.order_no,'*','*')
    and b.eng_chg_level = IFSAPP.shop_ord_api.Get_Eng_Chg_Level(a.order_no,'*','*')
    and b.bom_type_db='M'  and a.order_no=c.order_no
    and A.order_no='1875272R'
    and A.contract='PPCD'

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