Question

我想运行一个SQL查询，其中我只有很少的项目及其类型，例如RENT，LEASE或PURCHASE。问题在于某些项目可能有也可能没有全部三个，而是其中任何一个或两个。但是，如果某项没有特定类型，我想返回NONE而不是Blank。

我当前的查询是：

select DISTINCT ITEM_ID,  UOM, LIST_PRICE from PRICELIST_TABLE
where item_id IN ('XYZ')
and PRICELIST_HDR in (select Pricelist_Hdr_Key from SMCFS93.YPM_PRICELIST_HDR where PRICELIST_NAME IN ('ALL') and SELLER_ORGANIZATION_CODE IN ('20'))

如何确保即使不存在特定类型的物品，我也不会得到任何帮助。例如

ITEM_ID   UOM        PRICE     
ITEMX     PURCHASE   0
ITEMX     RENT       NONE  # none if not exist

Answer 1

使用cross join生成行，然后使用left join引入所需的值：

with pl as (
      select DISTINCT ITEM_ID, UOM, LIST_PRICE
      from PRICELIST_TABLE
      where item_id IN ('XYZ') and
            PRICELIST_HDR in (select Pricelist_Hdr_Key
                              from SMCFS93.YPM_PRICELIST_HDR
                              where PRICELIST_NAME IN ('ALL') and
                                     SELLER_ORGANIZATION_CODE IN ('20')
                             )
      )
select i.item_id, u.uom, pl.list_price
from (select distinct item_id from pl) i cross join
     (select 'RENT' as uom from dual union all
      select 'LEASE' as uom from dual union all
      select 'PURCHASE' as uom from dual
     ) u left join
     pl
     on pl.item_id = i.item_id and pl.uom = u.uom;

cross join创建所有项目和您关心的uom类别的组合。 left join然后输入您想要的数据。

如果您要使用字符串'NONE'而不是NULL，则需要考虑类型。如果LIST_PRICE是字符串，则没问题：

coalesce(list_price, 'NONE') as list_price

如果没有，则需要转换值：

coalesce(to_char(list_price), 'NONE') as list_price

Answer 2

使用coalesce()

select DISTINCT ITEM_ID,  UOM, coalesce(to_char(LIST_PRICE),'None')
from PRICELIST_TABLE left join SMCFS93.YPM_PRICELIST_HDR 
on PRICELIST_HDR =Pricelist_Hdr_Key and PRICELIST_NAME ='ALL' 
and SELLER_ORGANIZATION_CODE ='20'
where item_id ='XYZ'

如果不存在该项目，则打印“无”

2 个答案: