Dbgrid.DataSource.DataSet function
lazarus / 16-Databases

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exdatis · 2012-06-02 10:35

Why expression:
  if DBGrid.DataSource.DataSet.IsEmpty then
     Showmessage('Empty set');//example
does not work, actually makes exception?
Thanks.
p.s. Is expression:
if not (DBGrid.DataSource.DataSet.Fields[index_of_field].Value = NULL)
then
  something;
is better way?
CT2.5, SQLdb, Firebird2.5, xubuntu(32 bit).

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otorres · 2012-06-02 16:27

Code: [Select]DBGrid.DataSource.DataSet.IsEmptyThis is a function of
the class that no works because the DataSet no have set's of data
internally, but if you need know if the DataSet have record use:
Code: [Select]IF DBGrid.Datasource.DataSet.RecordCount <> 0 THEN
//HAVE DATA

Regards.

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Leledumbo · 2012-06-02 17:38

Quotedoes not work, actually makes exception?My guess: the dataset
property is nil.

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exdatis · 2012-06-02 18:01

No, DBGrid have a DataSource, and a DataSource have a DataSet. Because
I use the same SQLQuery when I need a simple select query, I always
explicitly give properties(DataSet, DataSource, DisplayLabel,
DisplayFormat etc.).
  I tried
  if DBGrid.DataSource.DataSet.Active then
but unsuccessfully.
Thanks Leledumbo!
Regards!

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exdatis · 2012-06-02 18:04

Thank you, otorres! I'll try, for a minute!

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exdatis · 2012-06-02 18:19

Ohhhhh, I'm so stupid! 
Leledumbo was right! I forget, when I stop to use the query, I set
DataSet to nil. When DataSet is opened he has properly DataSet.
   My simulation was with closed query, where I want to stop the
user...
Thanks guys!