var
I: Integer;
begin
Query1.First;
for I := 0 to Query1.RecordCount - 1 do begin //不建议//容易被影响.
Query1.Next;
{};
end;
/////
Query1.First;
while not Query1.Eof do begin //建议
{ }
Query1.Next;
end;
end;
vat x:Tx;
x:=Tx.Create; //不建议，x可能被多次创建
x.....
x.Free;//不建议，x还指向某处
////////
vat x:Tx;
if not assigend(x) then
x:=Tx.Create; //建议，x为nil时才创建
x.....
x.free;
x:=nil; //建议，释放后指向nil,或用FreeAndNil(x)代替以上两句
