Set Connected to trueto establish a connection to an ADO data store without opening a dataset. Set Connected to false to close a connection. The default value for Connected is false. 

An application can check Connected to determine the current status of a connection. If Connected is true, the connection is active; if false, and the KeepConnection property is also false, then the connection is inactive. 

Connected can also be used in a program to determine the success of a call to the Open method (a true value in Connected) or the Close method (a false value).

with ADOConnection1 do begin
  Open;
if Connected then
    { connection successful }
else
    { connection unsuccessful };
end;

ADOConnection1->Open();
if (ADOConnection1->Connected)
  // connection successful
else
  // connection unsuccessful

Open 

Close 

ConnectionTimeout 

ConnectionString 

ConnectionObject 

ConnectOptions 

OnWillConnect 

OnConnectComplete