c# - Different databases in one transaction -

i'm using transactionblock code web application stores connection string in config.

until now, required write local db, , therefore, code worked. however, need data access method, write database using different connection string.

i've created new connection string in config file, i'm not sure how call , swap out.

the skeleton code have far is:

  public class transactionblock : idisposable {     private readonly bool _mfirsttransactionblock = false;     private bool _mdisposed = false;      public transactionblock(string connectionstringconfigkey = null)     {         if (connectionstringconfigkey != null && currenttransaction != null)             throw new exception("can't create new transactionblock specific connectionstring if within block.");          // open connection if haven't yet                   if (currenttransaction == null) // don't have transaction yet create one:         {             sqlconnection conn = new sqlconnection(connectionstring); // create new connection object connection string.             try             {                 conn.open();             }             catch (sqlexception ex)             {                 // severity 20 errors returned when there connection                 // problems, retry if severity 20.                 // don't worry deadlock errors in here - we're connecting                 // database, not running deadlocked.                 if (ex.class != 20) throw;                 // clear connection pool of connections related given connection string.                 sqlconnection.clearpool(conn);                 // try open connection once again, catching error.                 try { conn.open(); }                 catch { conn = null; }                 // if 2nd attempt failed, throw original exception.                 if (conn == null) throw;             }             currenttransaction = conn.begintransaction();             _mfirsttransactionblock = true;         }     }      public void commit()     {         if (_mfirsttransactionblock)         {             dispose(true);         }     }      public void dispose()     {         if (_mfirsttransactionblock)         {             dispose(false);         }     }      private void dispose(bool commit)     {         if (_mdisposed)             return; // committed , cleaned already.          try         {             var transaction = currenttransaction;             var connection = transaction.connection; // taking reference connection object rollback set null;              if (commit)             {                 transaction.commit();             }             else // rollback transaction if hasn't been commited.             {                 transaction.rollback();             }              if (connection != null)             {                 connection.close();                 connection.dispose();             }              transaction.dispose();         }         // ensure regardless of connection exceptions, state set disposed.         {             // remove current transaction context.             currenttransaction = null;             _mdisposed = true;         }     }      private static sqltransaction currenttransaction     {                 {             return currentcontext.getitem<sqltransaction>("__transaction");         }         set         {             currentcontext.setitem("__transaction", value);         }     }      public static sqlconnection connection     {         { return currenttransaction.connection; }     }     public static sqltransaction transaction     {         { return currenttransaction; }     }      private static string connectionstring;     public static string connectionstring     {                 {             if (string.isnullorempty(connectionstring))             {                 try                 {                     connectionstring = configurationmanager.connectionstrings["defaultconnection"].connectionstring ?? "";                 }                 catch (exception ex)                 {                     servicelogger.logerror("database: creating sql connection. can not find connection string. nothing work until resolved.");                     throw;                 }                 if (string.isnullorempty(connectionstring))                     servicelogger.logerror("database: creating sql connection. can not find connection string. nothing work until resolved.");                 else                     servicelogger.loginfo(string.format("database: creating sql connection. connection string: {0}", connectionstring));             }             return connectionstring;         }     }      #region currentcontext helper class     /// <summary>     /// helper class easy access appropriate context containers.     /// </summary>     private static class currentcontext     {         public static t getitem<t>(string key) t : class         {             if (httpcontext.current != null)             {                 return (t)httpcontext.current.items[key];             }             else             {                 return (t)callcontext.getdata(key);             }          }         public static void setitem(string key, object value)         {             if (httpcontext.current != null)             {                 httpcontext.current.items[key] = value;             }             else             {                 callcontext.setdata(key, value);             }         }     }     #endregion      /// <summary>     /// adds application name connection string, if missing.      /// </summary>     /// <param name="connectionstring"></param>     /// <returns>modified connection string</returns>     private static string addapplicationnameifmissing(string connectionstring)     {         if (connectionstring == null)             return null;         // if connection string hasn't been configured application name,         // add 1 (assumes application name not 1st element, unlikely have leading ';').         if (connectionstring.indexof(";application name=", stringcomparison.ordinalignorecase) >= 0)             return connectionstring;          // todo: if turns out slow perform on each query caching connection strings should added.         // take site name if run website or webservice otherwise take process path.         string appname = system.web.hosting.hostingenvironment.sitename ?? path.getfilenamewithoutextension(environment.getcommandlineargs()[0]);         return connectionstring += string.format("{0}application name={1}", connectionstring.endswith(";") ? "" : ";", appname);     }      private interface istructuredparam     {         datatable todatatable();     }      public sqlcommand createspcommand(string sql)     {         if (string.isnullorwhitespace(sql)) throw new argumentnullexception("sql");          sqltransaction tran = currenttransaction;         if (tran == null) throw new nullreferenceexception("currenttransaction");          sqlconnection conn = tran.connection;         if (conn == null) throw new nullreferenceexception("connection");          sqlcommand cmd = conn.createcommand();         if (cmd == null) throw new nullreferenceexception("command");          cmd.commandtext = sql;         cmd.commandtype = commandtype.storedprocedure;         cmd.transaction = tran;         return cmd;     }     public void addparameter(sqlcommand cmd, string name, sqldbtype type, int size, object value, bool isoutput)     {         var p = cmd.createparameter();         p.parametername = name;         p.sqldbtype = type;         p.size = size;          if (value == null)             p.value = dbnull.value;          else if (type == sqldbtype.structured)             p.value = ((istructuredparam)value).todatatable();          else             p.value = value;          p.direction = isoutput == false ? parameterdirection.input : parameterdirection.output;         cmd.parameters.add(p);     }      public void executeandmapreader(sqlcommand command, params action<idatareader>[] mappingmethods)     {         using (var reader = command.executereader())         {             int = 0;                         {                 while (reader.read())                 {                     if (reader.hasrows && mappingmethods != null && mappingmethods.any())                         mappingmethods[i](reader);                 }                 i++;             } while (reader.nextresult());             reader.close();         }     } }