Question

我有3个表，我想要联合所有，但只有两列能够显示数据。

SELECT Vehicle_ID, Total_Weight, date, bilty_No FROM harvesting
UNION
SELECT Vehicle_ID, Total_Weight, date, Bilty_No FROM Blade_Harvesting

我想添加另一个表，如下面但是给出错误

SELECT Vehicle_ID, Total_Weight, date, bilty_No FROM harvesting
UNION
SELECT Vehicle_ID, Total_Weight, date, Bilty_No FROM Blade_Harvesting
UNION
SELECT Vehicle_ID, Vehicle_Name FROM Vehicle

发出此错误：

使用UNION，INTERSECT或EXCEPT运算符组合的所有查询在目标列表中必须具有相同数量的表达式

Answer 1

您必须在所有UNION SELECT子句中指定相等的列：

   SELECT Vehicle_ID VehicleId, Total_Weight TotalWeight,date,bilty_No 
          biltyNo,'' VehicleName
   FROM harvesting 
   UNION ALL
   SELECT Vehicle_ID VehicleId, Total_Weight TotalWeight,date,Bilty_No 
          biltyNo ,'' VehicleName
   FROM Blade_Harvesting 
   UNION ALL
   SELECT Vehicle_ID VehicleId ,0 TotalWeight,'' date ,'' biltyNo 
          ,Vehicle_Name VehicleName
   FROM Vehicle

Answer 2

UNION中的每个SELECT语句必须具有相同的列数。列还必须具有类似的数据类型。每个SELECT语句中的列也必须具有相同的顺序

试试这个

SELECT Vehicle_ID,cast(Total_Weight as varchar),date,bilty_No FROM harvesting
UNION
SELECT Vehicle_ID,cast(Total_Weight as varchar),date,Bilty_No FROM Blade_Harvesting
union
select Vehicle_ID,Vehicle_Name,'','' from Vehicle

Answer 3

请用户：

SELECT Vehicle_ID，Total_Weight，date，Bilty_No，''AS Vehicle_Name FROM harvesting

UNION SELECT Vehicle_ID，Total_Weight，date，Bilty_No，''AS Vehicle_Name FROM Blade_Harvesting

UNION SELECT Vehicle_ID，'0'AS Total_Weight，NULL AS date，'0'AS Bilty_No，Vehicle_Name FROM Vehicle

具有特定列

3 个答案: