使用 SCHEMABINDING 更改函数用作带索引的计算字段的公式

Question

我有一个 table，带有 PERSISTED 和基于函数结果 (MyFunctionTest) 的索引计算字段 (Test)，例如：

CREATE TABLE [dbo].[TestTable] (
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Foo] [int] NOT NULL,
    [Test]  AS ([dbo].[MyFunctionTest]([Foo])) PERSISTED,
    CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

MyFunctionTest 是：

ALTER FUNCTION [dbo].[MyFunctionTest]
(
    @foo int
)
RETURNS int
WITH SCHEMABINDING
AS
BEGIN
    RETURN @foo * 2
END

如果我尝试更改函数，SQL 服务器显示错误

Cannot ALTER 'dbo.MyFunctionTest' it is being referenced by object 'TestTable'.

改变函数的唯一方法似乎是创建一个新函数来改变 table。

我也尝试删除 WITH SCHEMABINDING

Answer 1

您可以删除该列，更改函数，然后重新添加该列：

ALTER TABLE [dbo].[TestTable]
    DROP COLUMN [Test];

GO

ALTER FUNCTION [dbo].[MyFunctionTest]
(
    @foo int
)
RETURNS int
WITH SCHEMABINDING
AS
BEGIN
    RETURN @foo * 2
END
GO

ALTER TABLE [dbo].[TestTable]
    ADD [Test] AS ([dbo].[MyFunctionTest]([Foo])) PERSISTED

创建新函数还意味着您需要删除该列并将其添加回来，因为 computed columns can't be altered。

使用 SCHEMABINDING 更改函数用作带索引的计算字段的公式

Alter a function with SCHEMABINDING used as formula for a calculated field with index

sql

tsql

sql-server

sql-server-2005