Sources
Delphi Russian Knowledge Base
DRKB - это самая большая и удобная в использовании база знаний по Дельфи в рунете, составленная Виталием Невзоровым

Как сделать ADO-connection?

01.01.2007
uses 
  ComObj; 
 
function OpenConnection(ConnectionString: AnsiString): Integer; 
var 
  ADODBConnection: OleVariant; 
begin 
  ADODBConnection := CreateOleObject('ADODB.Connection'); 
  ADODBConnection.CursorLocation := 3; // User client 
  ADODBConnection.ConnectionString := ConnectionString; 
  Result          := 0; 
  try 
    ADODBConnection.Open; 
  except 
    Result := -1; 
  end; 
end; 
 
function DataBaseConnection_Test(bMessage: Boolean): AnsiString; 
var 
  asTimeout, asUserName, asPassword, asDataSource, ConnectionString: AnsiString; 
  iReturn: Integer; 
  OldCursor: TCursor; 
begin 
  OldCursor     := Screen.Cursor; 
  Screen.Cursor := crHourGlass; 
  asTimeout     := '150'; 
  asUserName    := 'NT_Server'; 
  asPassword    := 'SA'; 
  asDataSource  := 'SQL Server - My DataBase'; 
 
  ConnectionString := 'Data Source = ' + asDataSource + 
    'User ID = ' + asUserName + 
    'Password = ' + asPassword + 
    'Mode = Read|Write;Connect Timeout = ' + asTimeout; 
  try 
    iReturn := OpenConnection(ConnectionString); 
 
    if (bMessage) then 
    begin 
      if (iReturn = 0) then 
        Application.MessageBox('Connection OK!', 'Information', MB_OK) 
      else if (iReturn = -1) then 
        Application.MessageBox('Connection Error!', 'Error', MB_ICONERROR + MB_OK); 
    end; 
 
    if (iReturn = 0) then 
      Result := ConnectionString 
    else if (iReturn = -1) then 
      Result := ''; 
  finally 
    Screen.Cursor := OldCursor; 
  end; 
end; 
 
 
procedure TForm1.Button1Click(Sender: TObject); 
begin 
  DataBaseConnection_Test(True); 
end;

Взято с сайта https://www.swissdelphicenter.ch/en/tipsindex.php