以前写过一份数据库的ADOTable的连接函数，发上来给你看看
void __fastcall TForm8::Button1Click(TObject *Sender)
{
  if(Edit1->Text!="")
  {
  String fwq_name;
  fwq_name="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=学校数据库;Data Source=";
  fwq_name=fwq_name+Edit1->Text;

  Form1->ADOQuery1->ConnectionString=fwq_name;
  Form1->ADOTable1->ConnectionString=fwq_name;
  Form1->ADOTable2->ConnectionString=fwq_name;
  Form1->ADOTable3->ConnectionString=fwq_name;
  Form1->ADOTable4->ConnectionString=fwq_name;
  Form1->ADOTable5->ConnectionString=fwq_name;
  Form2->ADOQuery1->ConnectionString=fwq_name;
  Form3->ADOQuery1->ConnectionString=fwq_name;

  try
  {
   Form1->ADOTable1->Active=true;
   Form1->ADOTable2->Active=true;
   Form1->ADOTable3->Active=true;
   Form1->ADOTable4->Active=true;
   Form1->ADOTable5->Active=true;
  }
  catch(...)
  {
   ShowMessage("连接服务器失败");
  }
}
else ShowMessage("服务器名称不能为空");
Form8->Close();
}