[SOLVED]EXTERNAL SIGSEGV error

[Kevinn33]

im making a project and it was running smoothly, then suddenly it appear error after successfully compile.

please help me

Code: Pascal  [Select][+][-]

1. procedure TFSewa.Timer3Timer(Sender: TObject);
2. var
3.     data2 :String;
4. begin
5.   //cek isiloker
6.    zquery1.close;
7.    zquery1.SQL.Clear;
8.    zquery1.SQL.add('select * from uji1 where Noloker = 1 order by Tanggal desc limit 1');
9.    zquery1.ExecSQL;
10.    zquery1.open;
11.    while not zquery1.EOF do begin
12.     data2+=zquery1.FieldByName('Isiloker').AsString;
13.     zquery1.Next;
14.    end;
15.    zquery1.close;
16.    zquery1.SQL.Clear;
17.    zquery1.SQL.add('select * from uji1 where Noloker = 2 order by Tanggal desc limit 1');
18.    zquery1.ExecSQL;
19.    zquery1.open;
20.    while not zquery1.EOF do begin
21.     data2+=zquery1.FieldByName('Isiloker').AsString;
22.     zquery1.Next;
23.    end;
24.    zquery1.close;
25.    zquery1.SQL.Clear;
26.    zquery1.SQL.add('select * from uji1 where Noloker = 3 order by Tanggal desc limit 1');
27.    zquery1.ExecSQL;
28.    zquery1.open;
29.    while not zquery1.EOF do begin
30.     data2+=zquery1.FieldByName('Isiloker').AsString;
31.     zquery1.Next;
32.    end;
33.    zquery1.close;
34.    zquery1.SQL.Clear;
35.    zquery1.SQL.add('select * from uji1 where Noloker = 4 order by Tanggal desc limit 1');
36.    zquery1.ExecSQL;
37.    zquery1.open;
38.    while not zquery1.EOF do begin
39.     data2+=zquery1.FieldByName('Isiloker').AsString;
40.     zquery1.Next;
41.    end;
42.    zquery1.close;
43.    zquery1.SQL.Clear;
44.    zquery1.SQL.add('select * from uji1 where Noloker = 5 order by Tanggal desc limit 1');
45.    zquery1.ExecSQL;
46.    zquery1.open;
47.    while not zquery1.EOF do begin
48.     data2+=zquery1.FieldByName('Isiloker').AsString;
49.     zquery1.Next;
50.    end;
51.    zquery1.close;
52.    //perubahan isiloker ke warna GUI
53.    //loker1
54.    if data2[1]='1' then
55.     Shape1.Brush.Color := clRed
56.    else
57.     Shape1.Brush.Color := clGreen;
58.    //loker2
59.    if data2[2]='1' then
60.     Shape2.Brush.Color := clRed
61.    else
62.     Shape2.Brush.Color := clGreen;
63.    //loker3
64.    if data2[3]='1' then
65.     Shape3.Brush.Color := clRed
66.    else
67.     Shape3.Brush.Color := clGreen;
68.    //loker4
69.    if data2[4]='1' then
70.     Shape4.Brush.Color := clRed
71.    else
72.     Shape4.Brush.Color := clGreen;
73.    //loker5
74.    if data2[5]='1' then
75.     Shape5.Brush.Color := clRed
76.    else
77.     Shape5.Brush.Color := clGreen;
78. end;

[balazsszekely]

First of all you either use ExecSQL or Open. The former does not return a value the later does. For example when you wish to insert something in the database, you should go with ExecSQL, when you query something from the database go with Open.
Secondly it looks like your query did not return a value so data2(string) is empty. You cannot access data2[1], hence the sigsegv.  You have two choice:
1. Test if the query is empty
2. Test if data2 <> ''

[Kevinn33]

 thanks Getmem, i'll try it later after dinner 

[Kevinn33]

well i just found out it was because i use 2 zconnection in 2 form that connects to the same database table. so it sometimes crash
thanks for the advice Getnem