How to get results of a TQuery en Delphi?

DataBase

When I run the following query in a database:

SELECT T.ID
FROM TABLA T
WHERE ID=3

Resutl:

No rows returned

Now I try show message in Delphi say "The record not exist".

In the form I have a component TQuery call qValidacion successfully connected with database Oracle 11g.

Try 1

procedure TfPrueba.ButtonAceptarClick(Sender: TObject);
begin
    qValidacion.Close;
    qValidacion.SQL.Add('SELECT T.ID');
    qValidacion.SQL.Add('FROM TABLA T');
    qValidacion.SQL.Add('WHERE ID=3');
    qValidacion.Open;
    qValidacion.First;
    if (not qValidacion.Eof) then 
        begin
             ShowMessage('The record not exist'); //It Should display the message, but does not show
        end;
    qValidacion.SQL.Clear;
end;

---

If you want to check if they are any record in your Query don't use the qValidacion.EOF but qValidacion.IsEmpty

if (qValidacion.IsEmpty) then 
begin
  ShowMessage('The record not exist'); 
end;

The EOF Function is here for returning true when you reach the end of a DataSet. Example:

qValidacion.First;
while not qValidacion.eof do
begin
 // do Something with the current record.
 qValidacion.next
end;

Edit1: Using IsEmpty is indeed more clean. Thanks to Arioch 'The

链接地址: http://www.djcxy.com/p/35088.html

上一篇: WebBrowser未分配

下一篇: 如何获得Delphi的TQuery结果？