Determining what driver FireDAC uses for MSSQL connection

[Ron Schuster 0]

Is there a way to find out what driver (ODBC, SQL Native Client, etc. ) that FireDAC is actually using when establishing a connection to the MSSQL database? In the FireDAC connection all we get to specify is DriverID = MSSQL and FireDAC apparently chooses an appropriate driver based on what's available.

[Dmitry Arefiev 101]

uses
  FireDAC.Phys.ODBCWrapper;

procedure TForm252.Button1Click(Sender: TObject);
begin
  ShowMessage(TODBCConnection(FDConnection1.CliObj).DRIVER_NAME);
end;

https://docwiki.embarcadero.com/Libraries/Athens/en/FireDAC.Comp.Client.TFDCustomConnection.CliObj

Edited February 19 by Dmitry Arefiev

[Anders Melander 1782]

Seems like there's a bug in the documentation. Unfortunate.

Quote

 

// returns the ODBC driver DLL name for an ODBC-based connection
ShowMessage(TODBCConnection(FDConnection1.CliObj).DRIVER.NAME);

 

 

[Lars Fosdal 1791]

@Ron Schuster

You can explicitly control which driver you want to use.

I use this code to pick my faves.

class function TPSDFireDatabasePoolMSSQL.FindBestDriver(const Link: TFDPhysMSSQLDriverLink): String;
const // Constants copied from implementation section of FireDAC.Phys.MSSQL
  C_SQL_SERVER = 'SQL Server'; // DO NOT TRANSLATE
  C_2019_ODBC = 'ODBC DRIVER 19 FOR SQL SERVER'; // DO NOT TRANSLATE
  C_2018_ODBC = 'ODBC DRIVER 18 FOR SQL SERVER'; // DO NOT TRANSLATE
  C_2017_ODBC = 'ODBC DRIVER 17 FOR SQL SERVER'; // DO NOT TRANSLATE
  C_2016_ODBC = 'ODBC DRIVER 13 FOR SQL SERVER'; // DO NOT TRANSLATE
  C_2012_ODBC = 'ODBC DRIVER 11 FOR SQL SERVER'; // DO NOT TRANSLATE
{$IFDEF POSIX}
  C_FreeTDS = 'FreeTDS';
{$ENDIF}
{$IFDEF MSWINDOWS}
  C_2012_NC = 'SQL SERVER NATIVE CLIENT 11.0'; // DO NOT TRANSLATE
{$ENDIF}
var
  DriverList : TStringList;
  WantedList : TArray<String>;
  Driver: string;
begin
  Result := ''; // Blank = Default

  WantedList := {$IFDEF MSWINDOWS}
                  {$IFDEF SQLNative}
                    [C_2012_NC, C_2017_ODBC, C_2016_ODBC, C_2012_ODBC]
                  {$ELSE}
                    [C_2018_ODBC, C_2017_ODBC, C_2016_ODBC, C_2012_NC, C_2012_ODBC]
                 {$ENDIF}
               {$ENDIF}
               {$IFDEF POSIX}
                 [C_2018_ODBC, C_2017_ODBC, C_2016_ODBC, C_2012_ODBC, C_FreeTDS]
               {$ENDIF};

  DriverList := TStringList.Create;
  try
    Link.GetDrivers(DriverList);

    DebugOut('Available SQL drivers'); // DO NOT TRANSLATE
    for Driver in DriverList
     do DebugOut(' "' + Driver + '"');

    for var Wanted in WantedList
     do for Driver in DriverList
      do begin
        if CompareText(Wanted , Driver) = 0
        then begin
          DebugOut('Selected driver: "' + Driver + '"'); // DO NOT TRANSLATE
          BestDriver := Driver;
          Exit(Driver);
        end;
      end;
  finally
    DriverList.Free;
  end;
end;

which I then use to configure the connections

class function TPSDFireDatabasePoolMSSQL.CreateDriverLink(const aOwner: TComponent): TFDPhysDriverLink;
var
  Res: TFDPhysMSSQLDriverLink;
begin
  Res := TFDPhysMSSQLDriverLink.Create(aOwner);
  if BestDriver = ''
   then BestDriver := FindBestDriver(Res);
  Res.ODBCDriver := BestDriver;
  Result := Res;
end;

 

[Ron Schuster 0]

What would be the reason that I would want to assign a driver other than one FireDAC chooses by default?

[Lars Fosdal 1791]

@Ron Schuster - Sometimes, there may be more than one driver installed, and the default one may be one that is less performant.