sql server join仅从第二个表返回一行

Question

我有两个表，Vehicle和Reading。

车辆桌

VehicleId 名称 InitialReading

1. ABC 584
2. XYZ 900

阅读桌

ReadingId 日期 转换 VehicleId 阅读

1. 2014-09-01 1 1 1234
2. 2014-09-01 2 1 2230
3. 2014-09-02 1 1 2500
4. 2014-09-02 2 1 3004
5. 2014-09-03 2 1 5000
6. 2014-09-03 1 1 4000
7. 2014-09-01 1 2 1000

现在我在合并读数时遇到问题。 我正在表格中搜索VehicleId

例如， VehicleId=1 ，则输出必须采用以下格式。

Date Shift OpeningReading ClosingReading

2014-09-01 1 584  1234 (if there are no opening for this date, I have to fetch the initial reading)   
2014-09-01 2 1234 2230    
2014-09-01 1 2230 2500
2014-09-01 2 2500 3004
2014-09-01 1 3004 4000
2014-09-01 2 4000 5000

我已经尝试过CROSS APPLY

create table vehicle(vehicleId int identity(1,1),name varchar(25),initialReading int);
insert into vehicle values('ABC',584),('XYZ',900);


create table reading (readingId int identity(1,1),[date] date,vehicleId int,shiftId int,reading int);
insert into reading values ('2014-09-01',1,1,1234),('2014-09-01',1,2,2230), ('2014-09-02',1,1,2500),('2014-09-02',1,2,3004),('2014-09-03',1,2,5000),('2014-09-03',1,1,4000);

SQLFiddle说的实验

Answer 1

您已经有两个表了。现在您想要合并两个表，其中Vehicle id = 1

只需使用子查询

select R.Date R.Shift,(select V.Initial Reading From Vehicle V where v.Vehicle id =R.Vehicle Id) as Initial Reading , R.Reading as Closing Reading from Reading Where Vehicle id=@Vehicle id

or 

set @Vehicle id=1

select R.Date R.Shift,(select V.Initial Reading From Vehicle V where v.Vehicle id =R.Vehicle Id) as Initial Reading , R.Reading as Closing Reading from Reading Where Vehicle id=1