sql服務器評估一行到多行不重複

Question

謙虛我要求下一個問題的幫助。

我有這個很簡單。不知道如何用文字描述它，所以我會用圖像來做。

表服務

PERSONID  Service_id   chargeamount 
1    3     20.50 
2    4     80.50 
3    5     78.80 

表收費

service_id  payed   extracharges 
3    true    20.50 
4    true    80.50 
3    false    78.80 

如果有任何unpayed extracharge它必須證明真或假，如果服務ID不會在第二個表匹配它必須是在查詢中顯示空值或其他計算值

類似這樣的東西

PERSONID  Service_id   chargeamount      payed 
1    3     20.50        false 
2    4     80.50        true 
3    5     78.80        null 

但同一行的額外行不允許像連接創建的那些行。

SET ANSI_NULLS ON 
GO 

SET QUOTED_IDENTIFIER ON 
GO 

CREATE TABLE [dbo].[SERVICES](
    [personid] [int] NULL, 
    [service_id] [int] NULL, 
    [chargeamount] [float] NULL 
) ON [PRIMARY] 

GO 


insert into services (personid,service_id,chargeamount) values (1,3 ,20); 
insert into services (personid,service_id,chargeamount) values (2,4 ,20); 
insert into services (personid,service_id,chargeamount) values (3,5 ,20); 



SET ANSI_NULLS ON 
GO 

SET QUOTED_IDENTIFIER ON 
GO 

CREATE TABLE [dbo].[charges](
    [payed] [bit] NULL, 
    [service_id] [int] NULL, 
    [extracharges] [float] NULL 
) ON [PRIMARY] 

GO 

insert into services (service_id,payed,extracharges) values (3,true,20.50); 
insert into services (service_id,payed,extracharges) values (3,false,78.80); 
insert into services (service_id,payed,extracharges) values (4,false,80.50); 

Answer 1

這是一個簡單的左連接service_id。當存在至少一行payed = false時，將顯示false。否則分別顯示true或null。

select s.*, case min(c.payed) when 1 then 'true' when 0 then 'false' else 'null' end 
from services s 
left join charges c on c.service_id = s.service_id 
group by s.personid, s.service_id, s.chargeamount 

SQLFiddle