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。

我知道这个帖子有点老了，但在我找到我正在寻找的答案之前，我就看到了这个帖子，我想分享一下。如果您正在使用SQLExpress(或localdb)，有一种更简单的方法来查找实例名。 在命令行类型中:

> sqllocaldb i

这将列出您在本地安装的实例名。因此，您的完整服务器名称应该在要连接的实例名称前面包含(localdb)\。此外，sqllocaldb允许您创建或删除实例以及配置它们。参见:SqlLocalDB Utility。

将获得SQL server的实例 reg查询“HKLM\软件\Microsoft\Microsoft SQL Server\实例名称\SQL”

或使用 SQLCMD - l

If you just want to see what's installed on the machine you're currently logged in to, I think the most straightforward manual process is to just open the SQL Server Configuration Manager (from the Start menu), which displays all the SQL Services (and only SQL services) on that hardware (running or not). This assumes SQL Server 2005, or greater; dotnetengineer's recommendation to use the Services Management Console will show you all services, and should always be available (if you're running earlier versions of SQL Server, for example).

If you're looking for a broader discovery process, however, you might consider third party tools such as SQLRecon and SQLPing, which will scan your network and build a report of all SQL Service instances found on any server to which they have access. It's been a while since I've used tools like this, but I was surprised at what they found (namely, a handful of instances that I didn't know existed). YMMV. You might Google for details, but I believe this page has the relevant downloads: http://www.sqlsecurity.com/Tools/FreeTools/tabid/65/Default.aspx

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

如果你在SSMS内，你可能会发现它更容易使用:

SELECT @@Version