我有两张桌子：
Dates: |ReportHeader| -------------- | 2015-04| | 2015-05| | 2015-06| Data: |ReportHeader|Customer|Sales| ----------------------------- | 2015-04| Plop| 684| | 2015-06| Plop| 486|
我有我的疑问：
select
Dates.ReportHeader,
Data.Customer,
Data.Sales
from Dates
left outer join data on Dates.ReportHeader = Data.ReportHeader
我期待的是：
|ReportHeader|Customer|Sales| ----------------------------- | 2015-04| Plop| 684| | 2015-05| null| null| | 2015-06| Plop| 486|
我得到的结果是：
|ReportHeader|Customer|Sales| ----------------------------- | 2015-04| Plop| 684| | 2015-06| Plop| 486|
有没有理由找到为什么这个左连接会像内连接一样？ 或者我只是不明白左连接应该如何工作。
我使用的Oracle版本是： Oracle Database 12c标准版12.1.0.2.0版 - 64位生产
提前感谢您提供的任何帮助
编辑： 似乎我已经过度简化了问题所以我最好把整个查询放在这里：
WITH
L0 AS (SELECT 1 C from dual UNION ALL SELECT 1 O from dual),
L1 AS (SELECT 1 C FROM L0 A CROSS JOIN L0 B),
L2 AS (SELECT 1 C FROM L1 A CROSS JOIN L1 B),
L3 AS (SELECT 1 C FROM L2 A CROSS JOIN L2 B),
L4 AS (SELECT 1 C FROM L3 A CROSS JOIN L3 B),
Nums AS (SELECT 0 N FROM dual union SELECT ROW_NUMBER() OVER ( ORDER BY (SELECT NULL from dual) ) N FROM L4),
Dates as (
select distinct
to_char(to_date(last_day(current_timestamp + (-1 * N))) , 'yyyy-MM') as ReportHeader,
to_date(add_months(last_day(current_timestamp + (-1 * N)),-1)+1) as FirstDayOfMonth,
to_date(current_timestamp + (-1 * N)) as ReportDate,
to_date(last_day(current_timestamp + (-1 * N))) as LastDayOfMonth
from Nums
where N <= 3 * 365
), Invoices AS (
select
TP.ID,
TP.Name,
h.FORMATTEDINVOICENUMBER,
l.SCHEDULEID,
to_date(h.INVOICEDUEDATE) as date_due,
to_date(L.EFFECTIVEDATEFULLYPAID) as date_payed
from ODSTHIRDPARTY TP
LEFT JOIN ODSINVOICELINE L on L.INVCUSID = TP.ID
LEFT JOIN ODSINVOICEHEADER H on h.ID = l.INVOICEHEADERID
where TP.NAME not in ('<None>','<Unknown>')
), data as (
select distinct
Invoices.Name as Customer,
Dates.ReportHeader,
count(distinct Invoices.SCHEDULEID) over (partition by Dates.ReportHeader, Invoices.Name) as NumContracts,
floor(avg(
case
when Invoices.date_due > Dates.LastDayOfMonth THEN 0
when coalesce(Invoices.date_payed, current_date) < Dates.FirstDayOfMonth THEN 0
when Invoices.date_payed < Invoices.date_due then Invoices.date_payed - Invoices.date_due
else to_date(least(coalesce(Invoices.date_payed, current_date), Dates.LastDayOfMonth )) - to_date(Invoices.date_due)
end
) over (partition by Dates.ReportHeader, Invoices.Name)) past_due,
Dates.FirstDayOfMonth as ReportStartDate,
Dates.LastDayOfMonth as ReportEndDate,
coalesce(Invoices.date_payed, current_date) as calc_date
from Dates
left join Invoices on Dates.ReportDate between Invoices.date_due and coalesce(Invoices.date_payed, current_date)
where coalesce(Invoices.date_payed, current_date) >= Invoices.date_due
)
select distinct
Dates.ReportHeader,
data.Customer,
data.NumContracts,
data.past_due
from Dates
left join data on data.ReportHeader = Dates.ReportHeader
order by data.Customer,dates.ReportHeader
麻烦的部分是最后的查询。 从左边的日期中选择加入数据
对于那些感兴趣的人，正如@APC在评论中所说的那样。创建一个可测试的用例。这样做会触发我重写现在可以正常工作的完整查询。我最初的前提是错误的，我采取了一个错误的初步方法。
以下修订查询：
WITH
L0 AS (SELECT 1 C from dual UNION ALL SELECT 1 O from dual),
L1 AS (SELECT 1 C FROM L0 A CROSS JOIN L0 B),
L2 AS (SELECT 1 C FROM L1 A CROSS JOIN L1 B),
L3 AS (SELECT 1 C FROM L2 A CROSS JOIN L2 B),
L4 AS (SELECT 1 C FROM L3 A CROSS JOIN L3 B),
Nums AS (SELECT 0 N FROM dual union SELECT ROW_NUMBER() OVER ( ORDER BY (SELECT NULL from dual) ) N FROM L4),
Dates as (
select distinct
to_char(to_date(last_day(current_timestamp + (-1 * N))), 'yyyy-MM') as ReportHeader,
to_date(add_months(last_day(current_timestamp + (-1 * N)), -1) + 1) as FirstDayOfMonth,
to_date(current_timestamp + (-1 * N)) as ReportDate,
to_date(last_day(current_timestamp + (-1 * N))) as LastDayOfMonth
from Nums
where N <= 2 * 365
), ThirdParties as (
select distinct
TP.ID,
TP.Name,
Dates.ReportHeader,
Dates.FirstDayOfMonth,
Dates.ReportDate,
Dates.LastDayOfMonth
from ODSTHIRDPARTY TP
cross join Dates
where TP.NAME not in ('<None>','<Unknown>')
), Invoices AS (
select distinct
TP.ID,
TP.Name,
TP.ReportHeader,
TP.FirstDayOfMonth,
OH.FORMATTEDINVOICENUMBER,
TP.LastDayOfMonth,
il.SCHEDULEID,
to_date(il.invoiceReferenceDate) as date_due,
to_date(iL.EFFECTIVEDATEFULLYPAID) as date_payed,
case
when il.id is null then 0
else
case
when to_date(il.invoiceReferenceDate) <= to_date(coalesce(iL.EFFECTIVEDATEFULLYPAID,least(current_date,tp.LastDayOfMonth))) then
to_date(coalesce(iL.EFFECTIVEDATEFULLYPAID,least(current_date,tp.LastDayOfMonth))) - to_date(il.invoiceReferenceDate)
else 0
end
end as daysLate
from ThirdParties TP
LEFT JOIN ODSINVOICELINE IL on IL.INVCUSID = TP.ID and TP.ReportDate
between il.invoiceReferenceDate and coalesce(il.EFFECTIVEDATEFULLYPAID, current_date)
left join ODSINVOICEHEADER OH on IL.INVOICEHEADERID = OH.ID
), data as (
select distinct
Invoices.ReportHeader,
Invoices.Name as Customer,
count(distinct Invoices.SCHEDULEID) over (partition by Invoices.ReportHeader, Invoices.Name) as NumContracts,
floor(avg(
case
when Invoices.date_due > Invoices.LastDayOfMonth THEN 0
when coalesce(Invoices.date_payed, current_date) < Invoices.FirstDayOfMonth THEN 0
when Invoices.date_payed < Invoices.date_due then Invoices.date_payed - Invoices.date_due
else to_date(least(coalesce(Invoices.date_payed, current_date), Invoices.LastDayOfMonth )) - to_date(Invoices.date_due)
end
) over (partition by Invoices.ReportHeader, Invoices.Name)) past_due,
Invoices.FirstDayOfMonth as ReportStartDate,
Invoices.LastDayOfMonth as ReportEndDate,
coalesce(Invoices.date_payed, current_date) as calc_date
from Invoices
-- and coalesce(Invoices.date_payed, current_date) >= Invoices.date_due
order by Invoices.Name, Invoices.reportheader
), upvt as (
select distinct
row_number()
over (
partition by customer
order by ReportHeader ) as ColNum,
data.ReportHeader ColName,
data.Customer,
data.NumContracts,
data.past_due
from data
), pvt as (
select * from (
select Customer, ColName, ColNum, NumContracts, past_due from upvt
) pivot (
MAX(past_due) as DueDays, MAX(NumContracts) as Contracts, Max(ColName) as ColName
for ColNum in ( '1', '2', '3', '4', '5', '6', '7', '8', '9','10','11','12','13','14','15',
'16','17','18','19','20','21','22','23','24')) pvt
)
select
row_number() over (order by Customer) as No,
pvt.*
from pvt;
答案 0 :(得分：-2)
使用以下查询
select
Dates.ReportHeader,
Data.Customer,
Data.Sales
from
Dates, Data
where
Dates.ReportHeader = Data.ReportHeader(+)