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Mac Davis
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 Posted: Fri Nov 04, 2005 3:05 am Post subject: Fields not available after recordset is opened |
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The following returns the correct number of records in recordcount, but I
am unable to access any of the fields.
with dm.dst_Name do begin
close;
commandtext := 'Select *, streetno, streetname from reslist, lots
where reslist.lotno = lots.lotno and lname like ' + quotedstr (stLname+'%');
commandText := commandtext + ' order by lname,fname';
open;
//ShowMessage (dm.dst_name.fieldbyname ('streetname').asstring);
statusbar1.Panels[0].Text := inttostr (recordcount);
end;
As soon as I uncomment the showMessage, I receive the following debugger
Exception Notification
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Debugger Exception Notification
---------------------------
Project ResList.exe raised exception class EDatabaseError with message
'dst_Name: Field 'streetname' not found'.
---------------------------
Break Continue Help
---------------------------
What am I doing wrong?
Thanks,
Mac
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Mac Davis
Guest
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| Posted: Fri Nov 04, 2005 2:59 pm Post subject: Re: Fields not available after recordset is opened |
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Does this mean that I can't have a calculated field when I'm selecting from
two tables?
-Mac-
"Brian Bushay TeamB" <BBushay (AT) Nmpls (DOT) com> wrote
| Quote: |
The following returns the correct number of records in recordcount, but I
am unable to access any of the fields.
with dm.dst_Name do begin
close;
commandtext := 'Select *, streetno, streetname from reslist, lots
where reslist.lotno = lots.lotno and lname like ' + quotedstr
(stLname+'%');
commandText := commandtext + ' order by lname,fname';
open;
//ShowMessage (dm.dst_name.fieldbyname ('streetname').asstring);
statusbar1.Panels[0].Text := inttostr (recordcount);
end;
As soon as I uncomment the showMessage, I receive the following debugger
Exception Notification
---------------------------
Debugger Exception Notification
---------------------------
Project ResList.exe raised exception class EDatabaseError with message
'dst_Name: Field 'streetname' not found'.
---------------------------
Break Continue Help
---------------------------
What am I doing wrong?
You must have persistent fields defined for your dataset component that do
not
include the streetname field. When you have persistent fields defined only
those
defined fields are available.
--
Brian Bushay (TeamB)
[email]Bbushay (AT) NMPLS (DOT) com[/email]
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Bill Todd
Guest
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| Posted: Fri Nov 04, 2005 3:43 pm Post subject: Re: Fields not available after recordset is opened |
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No. You can have calculated fields in any result set. Double click the
ADODataSet to open the fields editor and see if streetname is listed.
If there are fields listed but streetname is not among them right click
in the fields editor and add streetname.
--
Bill Todd (TeamB)
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Mac Davis
Guest
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| Posted: Sat Nov 05, 2005 4:36 pm Post subject: Re: Fields not available after recordset is opened |
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Thanks gentelmen!
"Brian Bushay TeamB" <BBushay (AT) Nmpls (DOT) com> wrote
| Quote: |
Does this mean that I can't have a calculated field when I'm selecting
from
two tables?
No. But you will have to define persistent fields for each table and the
calculated fields for each table.
You can define persistent fields in code like this
var
f : TField;
i : integer;
begin
Query1.FieldDefs.Update
Query1.Close;
for i := 0 to Query1.FieldDefs.Count - 1 do
//create persistent field that do not exist
if Query1.FindField(Query1.FieldDefs[i].Name) = nil then
Query1.FieldDefs.Items[i].CreateField(Query1);
//create a calculated field
f := TStringField.Create(Query1);
f.Name := 'Query1CalcField';
f.FieldName := 'CalcField';
f.DisplayLabel := 'CalcField';
f.Calculated := True;
f.DataSet := Query1;
Query1.Open;
end;
--
Brian Bushay (TeamB)
[email]Bbushay (AT) NMPLS (DOT) com[/email]
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