Question

谦卑地，我在下一个问题上寻求帮助。

我非常简单。不知道如何用文字描述它，所以我会用图像来做。

表格服务

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

表费用

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

如果有任何未计费的额外费用，则必须显示true或false，如果服务ID在第二个表中不匹配，则必须在查询中显示空值或其他计算值

像这样的东西

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

但不允许使用与连接创建的行相同的行。

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

这是service_id上的简单左连接。当至少有一行payed = false时，会显示false。否则，将分别显示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

sql server评估一个到多个行，没有重复项

1 个答案: