Pregunta
I am a beginner in Delphi and I need help with the following problem. I have to implement an editable DBGrid on my form. The DBGrid displays results from a query joining 3 tables. I managed to make the DBGrid editable but the edits have no effect on the database. I can insert, edit or delete rows in the DBGrid but these changes do not get saved to the database. I have the following settings:
Query2.DatabaseName=Test
Query2.SQL=SELECT cd.hourstart, cd.hourfinish, o.objname, cd."work", cd.worktime
FROM Card c JOIN CardDetail cd ON c.N=cd.card
JOIN objects o ON cd.project=o.N
WHERE c.worker=5 AND c.data=CONVERT(DATE, GETDATE())
Query2.UpdateObject=UpdateSQL2
Query2.CachedUpdates=True
Query2.RequestLive=True
UpdateSQL2.DeleteSQL=delete from CardDetail
where hourstart = :OLD_houerstart and
hourfinish = :OLD_houerfinish and
work = :OLD_work and
worktime = :OLD_worktime
UpdateSQL2.InsertSQL=...
UpdateSQL2.ModifySQL=...
DataSource2.DataSet=Query2
DBGrid2.DataSource=DataSource2
I am probably missing something but I don't know what. Any help would be appreciated!
Solución
It is claimed that you need several UpdateSQL object, one per table http://docwiki.embarcadero.com/RADStudio/XE3/en/Using_Multiple_Update_Objects_Index
Each of those objects should have base TDataSet bound to them for referencing vanilla data. http://docwiki.embarcadero.com/Libraries/en/Bde.DBTables.TDataSetUpdateObject.DataSet
It is claimed, that ApplyUpdates/Commit/CommitUpdates should be called on different objects in proper order. http://docwiki.embarcadero.com/RADStudio/en/Applying_Cached_Updates_with_Dataset_Component_Methods
PS. BDE is deprecated and badly compatble with recent Windows and recent db servers.
Otros consejos
// Have a look at the below code, it uses an AdoCommand
procedure DoSomething(DataSet: TDataSet);
var
ADOCommand : TADOCommand;
begin
ADOCommand:=TADOCommand.Create(nil);
try
try
ADOCommand.Connection:=Conn;
ADOCommand.Parameters.Clear;
Conn.BeginTrans;
if dataset.State = dsinsert then
begin
ADOCommand.CommandText := //Your insert statement
ADOCommand.ParamCheck:=False;
ADOCommand.Execute;
end
else
if DataSet.State = dsEdit then
begin
ADOCommand.CommandText := //Your edit statement
ADOCommand.ParamCheck:=False;
ADOCommand.Execute;
end
else
Begin
ADOCommand.CommandText := //Your delete statement
ADOCommand.ParamCheck:=False;
ADOCommand.Execute;
End;
Conn.CommitTrans;
except
on E : Exception do
begin
Conn.RollbackTrans;
MessageDlg('An exception occured, Error Class: ' + E.ClassName +#13+ 'ErrorMessage: '+ E.Message , mtError, [mbOK], 0);
Abort;
end;
end;
finally
ADOCommand.Free;
end;
end;