Delphi ошибка at beginning of table

Val Marinov seems to have given you a good answer to your question.
I just want to add
some points that don’t directly answer your question but may help you avoid making some mistakes.

You have some code

self.ListBox1.ItemIndex := Random(ListBox1.Items.Count)

which you want to use to set the listbox’s ItemIndex to a random, valid value. There are a couple of things which are asking for trouble about this:

1. Wrong way to use Random

The online help for the Random function says

In Delphi code, Random returns a random number within the range 0 <= X < Range. If Range is not specified, the result is a real-type random number within the range

0 <= X < 1.

For a ListBox, the range of valid ItemIndex values is 0..Items.Count - 1. But Random can return a fractional part, so a better way to write what you want is:

ListBox1.ItemIndex := Trunc(Random(ListBox1.Items.Count));

Called like that, Random will return a value below ListBox1.Items.Count, and the call to Trunc discards the fractional part.

2. Unnecessary use of self.

Your code is liberally sprinkled with the self qualifier. Having to use self like that is usually a sign of bad or sloppy coding.
In your TForm1.AddALL, the self in the first line tells the compiler that the instance of ListBox1 you are referring to is the one which is the TListBox component on your TForm1, rather than some other ListBox1 variable which may also be in scope (e.g. a global variable called ListBox1) when the line is compiled. But the way to avoid that problem is to avoid having the other ListBox1 in scope in the first place.
I suggest you simply delete all the instances of self., because you shouldn’t need to have them.

3. Avoid setting dataset RecordNumber

Finally, don’t get into the habit of relying on the fact that TClientDataSet allows you to specify a value for RecordNumber, it is rarely a good idea and few dataset types support it.
If you want to go to a random record, better use

Dataset.First;
DataSet.MoveBy(Random(X));

I leave it to you to work out what the argument X to Random should be, to move to a valid, random, record, based on what the online help says about Random.

← →
kvcomp
 
(2002-03-31 12:21)
[0]

Уже пятый день прошу помочь — никто не дает вразумительного ответа, или перевелись мастаки на Руси?!

Что за ошибка «At beginning of table», которая возникает при выполнении Table1.Edit; (записи в таблице есть)

P.S. Если можно, подробней.

← →
Lusha
 
(2002-03-31 12:43)
[1]

← →
kvcomp
 
(2002-03-31 23:17)
[2]

← →
Lusha
 
(2002-04-01 09:14)
[3]

← →
kvcomp
 
(2002-04-01 19:55)
[4]

← →
Malder
 
(2002-04-02 00:22)
[5]

← →
Lusha
 
(2002-04-02 09:03)
[6]

← →
Johnmen
 
(2002-04-02 09:24)
[7]

вероятно TSt.Open перед TSt.Edit

← →
Lusha
 
(2002-04-02 09:28)
[8]

>Johnmen

Гы-гы. Об этом я как то не подумал…

← →
Ka$per
 
(2002-04-02 09:44)
[9]

а не проще через SQL

«update table1 set foto=null where id=»value» «

← →
Ромик
 
(2002-04-02 10:55)
[10]

Проверь, точно ли твой грид связан ИМЕННО с той таблицей, которой даешь Edit. А то может «бегаешь» по одному набору

данных, а ждешь что в другом позиция изменится.

Если хочешь — бросай проект с базой по мылу. У меня сегодня время есть, глядишь вместе разберемся

← →
Mastadon
 
(2002-04-04 09:17)
[11]

Есть компоненты Clientdataset, Datasourse и DBgrid в связке. База сохранена в cds.
Ошибка возникает при запуске приложения, причем не указывает на строку в коде.

Может быть ошибка гдето здесь так как при откате ошибка изчезает (я коменчу эту часть кода и убираю cds файл из clientdataset1 из поля filename):

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  if s[1] = 'Y' then begin
      Delete(s, 1, 1);
      clientdataset1.Locate('Friend List',UpperCase(s),[]);
      clientdataset1.Edit;
      clientdataset1.Fields[0].AsString:=clientdataset1.Fields[0].AsString+' (online)';
      clientdataset1.post;
    end
    else
    begin
      Delete(s, 1, 1);
      clientdataset1.Locate('Friend List',UpperCase(s),[]);
      clientdataset1.Edit;
      clientdataset1.Fields[0].AsString:=clientdataset1.Fields[0].AsString+' (offline)';
      clientdataset1.post;
    end;

Не понимаю в чем ошибка, но если пропустить ее, то вроде дальше работает.

Нравится ресурс? Помоги проекту!

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