Как определить количество одинаковых записей после фильтрации методом SELECT DISTINCT?

SELECT  DISTINCT <поле> 
FROM <Таблица>

Label1->Caption = Query1->RecordCount;

ComboBox1->Items->Clear();
try{
MainForm->ADOQuery1->SQL->Clear();
ComboBox1->Items->Clear();
MainForm->ADOQuery1->SQL->Add("SELECT DISTINCT Memory FROM Glavnaya");
 
MainForm->ADOQuery1->Open();
MainForm->ADOQuery1->First();
while(!MainForm->ADOQuery1->Eof)
{
ComboBox1->Items->Add(MainForm->ADOQuery1->FieldByName("Memory")->AsString);
MainForm->ADOQuery1->Next();
}
}catch(...){}
int i = ComboBox1->Items->Count;
Panel1->Caption = "Количество наименований размеров памяти: " + IntToStr(i);

SELECT  DISTINCT FIO     
FROM FIO_db

SELECT * FROM FROM FIO_db
WHERE FIO=:FIO

void __fastcall TForm1::FormCreate(TObject *Sender)
 
{
   Query1->Open();
 ComboBox1->Clear();
   for (Query1->First(); !Query1->Eof; Query1->Next())
       ComboBox1->Items->Add(Query1->FieldByName("FIO")->AsString);

void __fastcall TForm1::ComboBox1Change(TObject *Sender)
{
Query2->Close();
if(Query2->Prepared)
Query2->Prepare();
Query2->ParamByName("FIO")->AsString = ComboBox1->Text.c_str();
Query2->Open();
Label1->Caption = Query2->RecordCount;
}

 
try{
ComboBox1->Items->Clear();
Query2->SQL->Clear();
Query2->SQL->Add("SELECT DISTINCT FIO FROM имя_таблицы");
 
Query2->Open();
Query2->First();
while(!Query2->Eof)
{
ComboBox1->Items->Add(Query2->FieldByName("FIO")->AsString);
Query2->Next();
}
}catch(...){}
int i = ComboBox1->Items->Count;
Label1->Caption = IntToStr(i);