How to: Create, Alter, and Remove a Default in Visual Basic .NET
This section describes how to create a default, attach it to a column, alter it, detach it from a column, and drop it by using Visual Basic .NET.
The code example shows how to create one default that is simple text, and another default that is a Transact-SQL statement. The default must be attached to the column by using the BindToColumn method and detached by using the UnbindFromColumn method.
Creating, altering, and removing defaults
Start Visual Studio 2005.
From the File menu, select New Project. The New Project dialog box appears.
In the Project Types pane, select Visual Basic. In the Templates pane, select Console Application.
(Optional) In the Name box, type the name of the new application.
Click OK to load the Visual Basic console application template.
On the Project menu, select Add Reference item. The Add Reference dialog box appears. Select Browse and locate the SMO assemblies in the C:\Program Files\Microsoft SQL Server\90\SDK\Assemblies folder. Select the following files:
Microsoft.SqlServer.ConnectionInfo.dll
Microsoft.SqlServer.Smo.dll
Microsoft.SqlServer.SqlEnum.dll
Microsoft.SqlServer.SmoEnum.dll
On the View menu, click Code.-Or-Select the Module1.vb window to display the code window.
In the code, before any declarations, type the following Imports statements to qualify the types in the SMO namespace:
Imports Microsoft.SqlServer.Management.Smo Imports Microsoft.SqlServer.Management.CommonInsert the code that follows this procedure into the main program.
Run and build the application.
示例
'Connect to the local, default instance of SQL Server.
Dim srv As Server
srv = New Server
'Reference the AdventureWorks database.
Dim db As Database
db = srv.Databases("AdventureWorks")
'Define a Default object variable by supplying the parent database and the default name
'in the constructor.
Dim def As [Default]
def = New [Default](db, "Test_Default2")
'Set the TextHeader and TextBody properties that define the default.
def.TextHeader = "CREATE DEFAULT [Test_Default2] AS"
def.TextBody = "GetDate()"
'Create the default on the instance of SQL Server.
def.Create()
'Declare a Column object variable and reference a column in the AdventureWorks database.
Dim col As Column
col = db.Tables("SpecialOffer", "Sales").Columns("StartDate")
'Bind the default to the column.
def.BindToColumn("SpecialOffer", "StartDate", "Sales")
'Unbind the default from the column and remove it from the database.
def.UnbindFromColumn("SpecialOffer", "StartDate", "Sales")
def.Drop()
In Visual Basic, the type Default is in square parentheses to differentiate it from the Visual Basic keyword.
请参阅
概念
Creating, Altering, and Removing Defaults