基于多表sql的select语句答案

【问题标题】：Select statement based on multiple table sql基于多表sql的select语句
【发布时间】：2021-12-05 06:46:46
【问题描述】：

您好，我有下表

司机

| Id       | vehicleId     | Power         |
| -------- | --------------|-------------- |
| 123      | 2221          |112            |
| 124      | 2222          |111            |

车辆

 vehicleId| VehicleAvl|
| -------- | -------------- |
| 2221| Yes|
| 2222| Yes|

车辆国家

Id| vehicleId| VehicleField| VehicleValue |
| -------| -------- | -------------- | -------------- |
| 1 | 2221| Residence Country| USA|
| 2| 2221| Registered Country| USA|
| 3 | 2221| Available Country| CAN|
| 4| 2222| Residence Country| USA|

从上面我需要编写一个简单的选择查询，它将获取车辆所在国家/地区是否属于美国

我不需要返回任何列而不是简单的 Select 1

我只有 Driver 表 ID 作为输入，所以我该如何编写需求查询

SELECT 1 
  FROM Driver IES, Vehicle d1,
  
 
where     
 IES.id= :GID and d1.vehicleId= IES.vehicleId
 And (SELECT vehiclevalue AS RESIDENCE_COUNTRY
    FROM  VehicleCountry t2
    where t2.vehicleId=d1.vehicleId
    AND t2.vehiclefield= 'RESIDENCE COUNTRY'
    ) DR 
  AND (IES.POWER IS NOT NULL
  OR DR.RESIDENCE_COUNTRY   != 'USA'
  OR DR.RESIDENCE_COUNTRY   IS NULL)

【问题讨论】：

根据您的要求，您只需要 VehicleCountry 表。您可以根据您的条件执行 select 1 in case 语句。
不，我需要三个表的组合，因为我正在检查属于第一个和第二个表的其他字段。 ex AND (IES.POWER IS NOT NULL) 与第一张桌子有关，我手里只有第一张桌子的 ID

标签： sql oracle oracle11g

【解决方案1】：

这样的？请注意

您发布的示例数据格式不正确，所以我不太明白 vehiclecountry 表中哪个值属于哪个列
在您的示例中，由于两位司机的居住国是美国，我将最后一个值修改为 UK，只是为了有所作为
#1 - 15 行中的样本数据；查询从第 17 行开始

SQL> with
  2  driver (id, vehicleid) as
  3    (select 123, 2221 from dual union all
  4     select 124, 2222 from dual
  5    ),
  6  vehicle (vehicleid, vehicleavl) as
  7    (select 2221, 'yes' from dual union all
  8     select 2222, 'yes' from dual
  9    ),
 10  vehiclecountry (id, vehicleid, vehiclefield, vehiclevalue) as
 11    (select 1, 2221, 'Residence Country' , 'USA' from dual union all
 12     select 2, 2221, 'Registered Country', 'USA' from dual union all
 13     select 3, 2221, 'Available Country' , 'USA' from dual union all
 14     select 4, 2222, 'Residence Country' , 'UK'  from dual
 15    )
 16  --
 17  select nvl(max(1), 0) result
 18  from driver d join vehicle v on v.vehicleid = d.vehicleid
 19  join vehiclecountry c on c.vehicleid = v.vehicleid
 20  where c.vehiclefield = 'Residence Country'
 21    and c.vehiclevalue = 'USA'
 22    --
 23    and d.id = &par_driver_id;
Enter value for par_driver_id: 123

    RESULT
----------
         1

SQL> /
Enter value for par_driver_id: 124

    RESULT
----------
         0

SQL>

【讨论】：

【解决方案2】：

显示给定司机的车辆居住国：

select d.vehicleId, v.vehicleValue as residence_country
from driver d
join vehicleCountry vc on vc.vehicleId = d.vehicleId
  and vc.vehicleField = 'Residence Country'
where d.id = $id

相同，但仅限居住国家/地区为美国的车辆（因此无需显示国家/地区）：

select d.vehicleId
from driver d
join vehicleCountry vc on vc.vehicleId = d.vehicleId
  and vc.vehicleField = 'Residence Country'
  and vc.vehicleValue = 'USA'
where d.id = $id

【讨论】：

【解决方案3】：

SELECT 
  CASE vc.VehicleValue = 'USA' THEN 1 ELSE 0 END
FROM driver d
join vehicleCountry vc on vc.vehicleId = d.vehicleId

【讨论】：