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Connect to an Instance of SQL Server

  • Artikkeli

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics

The first programming step in a SQL Server Management Objects (SMO) application is to create an instance of the Server object and to establish its connection to an instance of Microsoft SQL Server.

You can create an instance of the Server object and establish a connection to the instance of SQL Server in three ways. The first is using a ServerConnection object variable to provide the connection information. The second is to provide the connection information by explicitly setting the Server object properties. The third is to pass the name of the SQL Server instance in the Server object constructor.

Using a ServerConnection object

The advantage of using the ServerConnection object variable is that the connection information can be reused. Declare a Server object variable. Then, declare a ServerConnection object and set properties with connection information such as the name of the instance of SQL Server, and the authentication mode. Then, pass the ServerConnection object variable as a parameter to the Server object constructor. It isn't recommended to share connections between different server objects at the same time. Use the Copy method to get a copy of the existing connection settings.

Setting Server object properties explicitly

Alternatively, you can declare the Server object variable and call the default constructor. As is, the Server object tries to connect to the default instance of SQL Server with all the default connection settings.

Providing the SQL Server instance name in the Server object constructor

Declare the Server object variable and pass the SQL Server instance name as a string parameter in the constructor. The Server object establishes a connection with the instance of SQL Server with the default connection settings.

Connection Pooling

Calling the Connect method of the ServerConnection object is unnecessary. After operations are completed, SMO automatically establishes connections when needed and return them to the connection pool. If you call the Connect method, the connection won't be released to the pool. To achieve that, you need to use the Disconnect method explicitly. Furthermore, you can acquire a nonpooled connection by adjusting the NonPooledConnection property of the ServerConnection object.

Multithreaded Applications

For multithreaded applications, a separate ServerConnection object should be used in each thread.

Connect to an Instance of SQL Server for RMO

Replication Management Objects (RMO) uses a slightly different method from SMO to connect to a replication server.

RMO programming objects require that a connection to an instance of SQL Server is made by using the ServerConnection object implemented by the Microsoft.SqlServer.Management.Common namespace. This connection to the server is made independently of an RMO programming object. It's then it's passed to the RMO object either during instance creation or by assignment to the ConnectionContext property of the object. In this manner, an RMO programming object and the connection object instances can be created and managed separately, and a single connection object can be reused with multiple RMO programming objects. The following rules apply for connections to a replication server:

  • All properties for the connection are defined for a specified ServerConnection object.

  • Each connection to an instance of SQL Server must have its own ServerConnection object.

  • All authentication information to make the connection and successfully sign in the server is supplied in the ServerConnection object.

  • By default, connections are made by using Microsoft Windows Authentication. To use SQL Server Authentication, LoginSecure must be set to False and Login and Password must be set to a valid SQL Server sign-in and password. Security credentials must always be stored and handled securely, and supplied at run time whenever possible.

  • The Connect method must be called before passing the connection to any RMO programming object.

Examples

To use any code example that is provided, you'll have to choose the programming environment, the programming template, and the programming language in which to create your application. For more information, see Create a Visual C# SMO Project in Visual Studio .NET.

Connect to the Local Instance of SQL Server by Using Windows Authentication in Visual Basic

Connecting to the local instance of SQL Server doesn't require much code. Instead, it relies on default settings for authentication method and server. The first operation that requires data to be retrieved causes a connection to be created.

This example is Visual Basic .NET code that connects to the local instance of SQL Server by using Windows Authentication.

'Connect to the local, default instance of SQL Server.
Dim srv As Server
srv = New Server
'The connection is established when a property is requested.
Console.WriteLine(srv.Information.Version)
'The connection is automatically disconnected when the Server variable goes out of scope.

Connect to the Local Instance of SQL Server by Using Windows Authentication in Visual C#

Connecting to the local instance of SQL Server doesn't require much code. Instead, it relies on default settings for authentication method and server. The first operation that requires data to be retrieved causes a connection to be created.

This example is Visual C# .NET code that connects to the local instance of SQL Server by using Windows Authentication.

{
//Connect to the local, default instance of SQL Server.
Server srv;
srv = new Server();
//The connection is established when a property is requested.
Console.WriteLine(srv.Information.Version);
}
//The connection is automatically disconnected when the Server variable goes out of scope.

Connect to a Remote Instance of SQL Server by Using Windows Authentication in Visual Basic

When you connect to an instance of SQL Server by using Windows Authentication, you don't have to specify the authentication type. Windows Authentication is the default.

This example is Visual Basic .NET code that connects to the remote instance of SQL Server by using Windows Authentication. The string variable strServer contains the name of the remote instance.

'Connect to a remote instance of SQL Server.
Dim srv As Server
'The strServer string variable contains the name of a remote instance of SQL Server.
srv = New Server(strServer)
'The actual connection is made when a property is retrieved.
Console.WriteLine(srv.Information.Version)
'The connection is automatically disconnected when the Server variable goes out of scope.

Connect to a Remote Instance of SQL Server by Using Windows Authentication in Visual C#

When you connect to an instance of SQL Server by using Windows Authentication, you don't have to specify the authentication type. Windows Authentication is the default.

This example is Visual C# .NET code that connects to the remote instance of SQL Server by using Windows Authentication. The string variable strServer contains the name of the remote instance.

{
//Connect to a remote instance of SQL Server.
Server srv;
//The strServer string variable contains the name of a remote instance of SQL Server.
srv = new Server(strServer);
//The actual connection is made when a property is retrieved.
Console.WriteLine(srv.Information.Version);
}
//The connection is automatically disconnected when the Server variable goes out of scope.

Connect to an Instance of SQL Server by Using SQL Server Authentication in Visual Basic

When you connect to an instance of SQL Server by using SQL Server Authentication, you must specify the authentication type. This example demonstrates the alternative method of declaring a ServerConnection object variable, which enables the connection information to be reused.

The example is Visual Basic .NET code that demonstrates how to connect to the remote and vPassword contain the sign-in and password.

' compile with:
' /r:Microsoft.SqlServer.Smo.dll
' /r:Microsoft.SqlServer.ConnectionInfo.dll
' /r:Microsoft.SqlServer.Management.Sdk.Sfc.dll
  
Imports Microsoft.SqlServer.Management.Smo
Imports Microsoft.SqlServer.Management.Common
  
Public Class A
   Public Shared Sub Main()
      Dim sqlServerLogin As [String] = "user_id"
      Dim password As [String] = "pwd"
      Dim instanceName As [String] = "instance_name"
      Dim remoteSvrName As [String] = "remote_server_name"
  
      ' Connecting to an instance of SQL Server using SQL Server Authentication
      Dim srv1 As New Server()   ' connects to default instance
      srv1.ConnectionContext.LoginSecure = False   ' set to true for Windows Authentication
      srv1.ConnectionContext.Login = sqlServerLogin
      srv1.ConnectionContext.Password = password
      Console.WriteLine(srv1.Information.Version)   ' connection is established
  
      ' Connecting to a named instance of SQL Server with SQL Server Authentication using ServerConnection
      Dim srvConn As New ServerConnection()
      srvConn.ServerInstance = ".\" & instanceName   ' connects to named instance
      srvConn.LoginSecure = False   ' set to true for Windows Authentication
      srvConn.Login = sqlServerLogin
      srvConn.Password = password
      Dim srv2 As New Server(srvConn)
      Console.WriteLine(srv2.Information.Version)   ' connection is established
  
      ' For remote connection, remote server name / ServerInstance needs to be specified
      Dim srvConn2 As New ServerConnection(remoteSvrName)
      srvConn2.LoginSecure = False
      srvConn2.Login = sqlServerLogin
      srvConn2.Password = password
      Dim srv3 As New Server(srvConn2)
      Console.WriteLine(srv3.Information.Version)   ' connection is established
   End Sub
End Class

Connect to an Instance of SQL Server by Using SQL Server Authentication in Visual C#

When you connect to an instance of SQL Server by using SQL Server Authentication, you must specify the authentication type. This example demonstrates the alternative method of declaring a ServerConnection object variable, which enables the connection information to be reused.

The example is Visual C# .NET code that demonstrates how to connect to the remote and vPassword contain the sign-in and password.

// compile with:
// /r:Microsoft.SqlServer.Smo.dll
// /r:Microsoft.SqlServer.ConnectionInfo.dll
// /r:Microsoft.SqlServer.Management.Sdk.Sfc.dll
  
using System;
using Microsoft.SqlServer.Management.Smo;
using Microsoft.SqlServer.Management.Common;
  
public class A {
   public static void Main() {
      String sqlServerLogin = "user_id";
      String password = "pwd";
      String instanceName = "instance_name";
      String remoteSvrName = "remote_server_name";
  
      // Connecting to an instance of SQL Server using SQL Server Authentication
      Server srv1 = new Server();   // connects to default instance
      srv1.ConnectionContext.LoginSecure = false;   // set to true for Windows Authentication
      srv1.ConnectionContext.Login = sqlServerLogin;
      srv1.ConnectionContext.Password = password;
      Console.WriteLine(srv1.Information.Version);   // connection is established
  
      // Connecting to a named instance of SQL Server with SQL Server Authentication using ServerConnection
      ServerConnection srvConn = new ServerConnection();
      srvConn.ServerInstance = @".\" + instanceName;   // connects to named instance
      srvConn.LoginSecure = false;   // set to true for Windows Authentication
      srvConn.Login = sqlServerLogin;
      srvConn.Password = password;
      Server srv2 = new Server(srvConn);
      Console.WriteLine(srv2.Information.Version);   // connection is established
  
      // For remote connection, remote server name / ServerInstance needs to be specified
      ServerConnection srvConn2 = new ServerConnection(remoteSvrName);
      srvConn2.LoginSecure = false;
      srvConn2.Login = sqlServerLogin;
      srvConn2.Password = password;
      Server srv3 = new Server(srvConn2);
      Console.WriteLine(srv3.Information.Version);   // connection is established
   }
}

See also

Server ServerConnection