procedure Tdm.DataModuleCreate(Sender: TObject);
begin
try
  FDConnection1.Connected := False;
  FDConnection1.Params.Database := ExtractFileDir(ParamStr(0)) + '\mdb\' + 'code.mdb';
  FDConnection1.Connected := True;
//FDConnection1.Close;
//FDConnection1.Connected:=True;
except on E: Exception do
 begin
 Tip.Show('提示',e.Message);
 end;
end;
end;

https://www.cnblogs.com/windson/p/12649724.html