当我评估100多个服务器时，我也遇到了同样的问题，我用c#写了一个脚本来浏览由SQL组成的服务名称。当在服务器上安装实例时，SQL server为每个实例添加一个服务，并使用服务名。对于不同的版本，例如2000年到2008年，它可能有所不同，但肯定有一个具有实例名的服务。

我获取服务名并从服务名获得实例名。下面是WMI查询结果的示例代码:

if (ServiceData.DisplayName == "MSSQLSERVER" || ServiceData.DisplayName == "SQL Server (MSSQLSERVER)")
            {
                InstanceData.Name = "DEFAULT";
                InstanceData.ConnectionName = CurrentMachine.Name;
                CurrentMachine.ListOfInstances.Add(InstanceData);
            }
            else
                if (ServiceData.DisplayName.Contains("SQL Server (") == true)
                {
                    InstanceData.Name = ServiceData.DisplayName.Substring(
                                            ServiceData.DisplayName.IndexOf("(") + 1,
                                            ServiceData.DisplayName.IndexOf(")") - ServiceData.DisplayName.IndexOf("(") - 1
                                        );
                    InstanceData.ConnectionName = CurrentMachine.Name + "\\" + InstanceData.Name;
                    CurrentMachine.ListOfInstances.Add(InstanceData);
                }
                else
                    if (ServiceData.DisplayName.Contains("MSSQL$") == true)
                    {
                        InstanceData.Name = ServiceData.DisplayName.Substring(
                                                ServiceData.DisplayName.IndexOf("$") + 1,
                                                ServiceData.DisplayName.Length - ServiceData.DisplayName.IndexOf("$") - 1
                                            );

                        InstanceData.ConnectionName = CurrentMachine.Name + "\\" + InstanceData.Name;
                        CurrentMachine.ListOfInstances.Add(InstanceData);
                    }

如果你在SSMS内，你可能会发现它更容易使用:

SELECT @@Version

安装的所有实例都应该显示在Microsoft管理控制台的服务管理单元中。如果需要获取实例名，请执行“开始|运行|类型的服务”。查找所有带有“Sql Server(实例名)”的条目。

——T-SQL查询查找机器上已安装的实例列表

DECLARE @GetInstances TABLE
( Value nvarchar(100),
 InstanceNames nvarchar(100),
 Data nvarchar(100))

Insert into @GetInstances
EXECUTE xp_regread
  @rootkey = 'HKEY_LOCAL_MACHINE',
  @key = 'SOFTWARE\Microsoft\Microsoft SQL Server',
  @value_name = 'InstalledInstances'

Select InstanceNames from @GetInstances 

这个查询可以得到服务器名和实例名:

SELECT @@SERVERNAME, @@SERVICENAME

SQL Server permits applications to find SQL Server instances within the current network. The SqlDataSourceEnumerator class exposes this information to the application developer, providing a DataTable containing information about all the visible servers. This returned table contains a list of server instances available on the network that matches the list provided when a user attempts to create a new connection, and expands the drop-down list containing all the available servers on the Connection Properties dialog box. The results displayed are not always complete. In order to retrieve the table containing information about the available SQL Server instances, you must first retrieve an enumerator, using the shared/static Instance property:

using System.Data.Sql;

class Program
{
  static void Main()
  {
    // Retrieve the enumerator instance and then the data.
    SqlDataSourceEnumerator instance =
      SqlDataSourceEnumerator.Instance;
    System.Data.DataTable table = instance.GetDataSources();

    // Display the contents of the table.
    DisplayData(table);

    Console.WriteLine("Press any key to continue.");
    Console.ReadKey();
  }

  private static void DisplayData(System.Data.DataTable table)
  {
    foreach (System.Data.DataRow row in table.Rows)
    {
      foreach (System.Data.DataColumn col in table.Columns)
      {
        Console.WriteLine("{0} = {1}", col.ColumnName, row[col]);
      }
      Console.WriteLine("============================");
    }
  }
}

来自MSDN http://msdn.microsoft.com/en-us/library/a6t1z9x2(v=vs.80).aspx