How to: Create, Alter, and Remove a Foreign Key in Visual Basic .NET
This section describes how to create, alter, and remove a foreign key in Visual Basic .NET.
The code example shows how to create a foreign key relationship between one or more columns in one table to a primary key column in another table.
Creating, altering, and removing foreign keys
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.
Esempio
'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")
'Declare a Table object variable and reference the Employee table.
Dim tbe As Table
tbe = db.Tables("Employee", "HumanResources")
'Declare another Table object variable and reference the EmployeeAddress table.
Dim tbea As Table
tbea = db.Tables("EmployeeAddress", "HumanResources")
'Define a Foreign Key object variable by supplying the EmployeeAddress as the parent table and the foreign key name in the constructor.
Dim fk As ForeignKey
fk = New ForeignKey(tbea, "test_foreignkey")
'Add EmployeeID as the foreign key column.
Dim fkc As ForeignKeyColumn
fkc = New ForeignKeyColumn(fk, "EmployeeID", "EmployeeID")
fk.Columns.Add(fkc)
'Set the referenced table and schema.
fk.ReferencedTable = "Employee"
fk.ReferencedTableSchema = "HumanResources"
'Create the foreign key on the instance of SQL Server.
fk.Create()
Vedere anche
Concetti
Creating, Altering, and Removing Foreign Keys