SQL Server 2012 上的可插入 UNION ALL VIEW

Posted 2023-02-26

【中文标题】SQL Server 2012 上的可插入 UNION ALL VIEW

【英文标题】：Insertable UNION ALL VIEW on SQL Server 2012

【发布时间】：2016-02-22 18:28:30

【问题描述】：

我已提供此架构且不可修改：

Table: Company1 Customers
+-------------+---------------+
| Customer ID | Customer Name |
+-------------+---------------+
| C0001       | ACME Inc.     |
| C0002       | Bogus Corp.   |
+-------------+---------------+

Table: Company2 Customers
+-------------+---------------+
| Customer ID | Customer Name |
+-------------+---------------+
| C0001       | Foo Bar Ltd.  |
| C0002       | John Smith    |
+-------------+---------------+

我需要这样的可插入/可更新/可删除视图：

View: All Customers
+----------+-------------+---------------+
| Company  | Customer ID | Customer Name |
+----------+-------------+---------------+
| Company1 | C0001       | ACME Inc.     |
| Company1 | C0002       | Bogus Corp.   |
| Company2 | C0001       | Foo Bar Ltd.  |
| Company2 | C0002       | John Smith    |
+----------+-------------+---------------+

我将其构建为：

CREATE VIEW [All Customers] AS
   SELECT 'Company1' AS [Company], [Customer ID], [Customer Name]
   FROM [Company1_Customers]
UNION ALL
   SELECT 'Company2' AS [Company], [Customer ID], [Customer Name]
   FROM [Company2_Customers]

如何（如果可能）告诉 SQL Server 在此视图中的所有 INSERT/UPDATE/DELETE 操作，其中[Company] = 'Company1' 属于Company1_Customers，[Company] = 'Company2' 属于Company2_Customers？

【问题讨论】：

If I update a view, will my original tables get updated的可能重复

【参考方案1】：

您可以通过为插入/更新/删除创建一个INSTEAD OF 触发器来做到这一点。

您可以检查inserted 和deleted 虚拟表以查看受影响的表，并根据此执行正确的语句。 INSTEAD OF DELETE 触发器示例：

CREATE TRIGGER trigger_delete_all_customers ON [All Customers]
INSTEAD OF DELETE
AS
BEGIN
    DELETE c 
    FROM deleted AS d 
         INNER JOIN Company1_Customers AS c ON
              c.[Customer ID]=d.[Customer ID]
    WHERE
        d.[Company]='Company1';

    DELETE c 
    FROM deleted AS d 
         INNER JOIN Company2_Customers AS c ON
              c.[Customer ID]=d.[Customer ID]
    WHERE
        d.[Company]='Company2';
END

有关创建INSTEAD OF 触发器的更多信息，请参阅documentation。

【参考方案2】：

从here 你会看到

“任何修改，包括 UPDATE、INSERT 和 DELETE 语句， 必须只引用一个基表中的列。”

每个字段都有两个基表，因为您的UNION 所以这个视图不能是“UPDATABLE”。

您最好的办法是修复您的架构并拥有一个 Customer 表，其中 Company 作为列之一。您当前需要 UNION 才能完全查询的架构不是最好的。