Пунктуация в динамическом SQL-запросе

   float min, max;
   min=a-0.01; max=a+0.01;
  ShowMessage(min);
  ShowMessage(max); // - здесь видно, что до этого места всё правильно
   Query1->Close();
   Query1->SQL->Clear();
   Query1->SQL->Text="Select Stoim From Tar_Setka Where Razr between '"+FloatToStr(min)+"' and '"+FloatToStr(max)+"'";

 Query1->SQL->Text="Select Stoim From Tar_Setka Where Razr between 1,5 and 1,8";

Query1->SQL->Text="Select Stoim From Tar_Setka Where Razr between "+FloatToStr(min)+" and "+FloatToStr(max)+"";

void __fastcall TForm1::Raznica()
 {
  float min = 1000, max = 2000;
  ADOQuery1->Close();
  ADOQuery1->SQL->Clear();
  //ADOQuery1->SQL->Add("SELECT * FROM Vklad WHERE Summa_vklada BETWEEN 1000 AND 2000");
  ADOQuery1->SQL->Add("SELECT * FROM Vklad WHERE Summa_vklada BETWEEN "+FloatToStr(min)+" AND "+FloatToStr(max)+"");
  ADOQuery1->Open();
 }

void __fastcall TForm1::Raznica()
 {
  float fmin = 1000, fmax = 2000;
  ADOQuery1->Close();
  ADOQuery1->SQL->Text = "SELECT * FROM Vklad WHERE Summa_vklada BETWEEN :p1 AND :p2";
  ADOQuery1->Parameters->ParamByName("p1")->Value = fmin;
  ADOQuery1->Parameters->ParamByName("p2")->Value = fmax;
  ADOQuery1->Open();
 }

a=Query1->FieldByName("Razr")->AsFloat;
   float min, max;
   min=a-0.01; max=a+0.01;
   Query1->Close();
   Query1->SQL->Clear();
   Query1->SQL->Text="Select Stoim From Tar_Setka Where Razr between :min And :max";
   Query1->Params->ParamByName("min")->Value=min;
   Query1->Params->ParamByName("max")->Value=max;
   Query1->Open(); 
   float b=Query1->FieldByName("Stoim")->AsFloat;