怎樣做sql server資料庫的還原

以下為引用的內容：   void restoreButton_Click(object sender, System.EventArgs e)    {     string path = pathTextBox.Text;     string dbname = dbDropDownList.SelectedValue;     string restoreSql = "use master;";     restoreSql += "restore database @dbname from disk = @path;";                 string pai = "use master;ALTER DATABASE Wy SET OFFLINE WITH ROLLBACK IMMEDIATE;ALTER DATABASE Wy SET ONLINE WITH ROLLBACK IMMEDIATE";                 SqlConnection conn = new SqlConnection(ConnStr);                 SqlCommand com1 = new SqlCommand(pai, conn);     SqlCommand myCommand = new SqlCommand(restoreSql, new SqlConnection(ConnStr));     myCommand.Parameters.Add("@dbname", SqlDbType.Char);     myCommand.Parameters["@dbname"].Value = dbname;     myCommand.Parameters.Add("@path", SqlDbType.Char);     myCommand.Parameters["@path"].Value = path;     try     {                     conn.Open();                     com1.ExecuteNonQuery();                     conn.Close();                     myCommand.Connection.Open();      myCommand.ExecuteNonQuery();                     infoLabel.Text = "恢複成功！<br>已經把備份"+path+"恢複到資料庫";     }     catch(Exception ex)     {                     infoLabel.Text = "恢複失敗！<br>出錯資訊如下：<br>" + ex.ToString();     }     finally     {      myCommand.Connection.Close();     }    }