内联函数，每个视图或函数中的列名必须是唯一的

Question

我加入了两个 table 现在我想在函数中保存该语句以便我可以再次使用它然后再次。我尝试按如下方式创建函数：-

create function fn_electricalsem1and2()
returns table
as
return (
      Select * 
      from [Electrical Semester 1 Regular] as T1 
      inner join[Electrical Semester 2 Regular] As T2 On T1.department_id= T2.department_id
)

现在我收到错误

Column names in each view or function must be unique. Column name 'Name' in view or function 'fn_electricalsem1and2' is specified more than once.

到现在为止我还没有做任何函数，但为什么我得到错误 function must be unique？

Answer 1

It is giving error because your function is returning a table and in a table all the column name should be unique.

要解决您需要更换的问题

Select *

至

Select t1.column1 as Col1, t1.column2, t2.column1 as Col2, ...and so on

在您的情况下，department_id 在两个 table 中都可用。 table 也都包含一个名称列：name.

Answer 2

在以下查询中，我们将首先创建表格并填充一些数据。

CREATE TABLE [Electrical Semester 1 Regular](department_id INT);
CREATE TABLE [Electrical Semester 2 Regular](department_id INT);
INSERT INTO [Electrical Semester 1 Regular]
VALUES(1);
INSERT INTO [Electrical Semester 2 Regular]
VALUES(1);

当我们执行以下查询时，您不会遇到任何错误；

 Select * 
 from [Electrical Semester 1 Regular] as T1 
      inner join[Electrical Semester 2 Regular] As T2 On T1.department_id= T2.department_id

+---------------+---------------+
| department_id | department_id |
+---------------+---------------+
|             1 |             1 |
+---------------+---------------+

但是，由于 [Electrical Semester 1 Regular] 和 [Electrical Semester 的列名相同，因此以下查询 returns 出错2 常规]。在 SQL 服务器中，如果我们想创建一个视图或函数，我们必须使用别名

提供唯一的名称

create function fn_electricalsem1and2()
returns table
as
return (
      Select * 
      from [Electrical Semester 1 Regular] as T1 
      inner join[Electrical Semester 2 Regular] As T2 On T1.department_id= T2.department_id
)

在 SQL 服务器中，如果我们想要创建一个视图或函数，我们必须提供唯一的名称。您可以使用别名启用它，这样您就可以像下面这样更改您的查询；

create function fn_electricalsem1and2()
returns table
as
return (
      Select t1.department_id as t1_department_id , t2.department_id as t2_department_id
      from [Electrical Semester 1 Regular] as T1 
      inner join[Electrical Semester 2 Regular] As T2 On T1.department_id= T2.department_id
)

GO
select * from fn_electricalsem1and2()


    +------------------+------------------+
    | t1_department_id | t2_department_id |
    +------------------+------------------+
    |                1 |                1 |
    +------------------+------------------+

内联函数，每个视图或函数中的列名必须是唯一的

Inline Function, Column names in each view or function must be unique

sql-server

inline-table-function