我创建了一个具有以下结构的FDMemTable:
Cds_NaMenu := TFDMemTable.Create(nil);
Cds_NaMenu.FieldDefs.Add('ID', ftInteger);
Cds_NaMenu.FieldDefs.Add('MN_TELA_CODIGO', ftInteger);
Cds_NaMenu.FieldDefs.Add('MN_MENU_PESQUISA', ftString, 500);
Cds_NaMenu.FieldDefs.Add('DISPONIBILIDADE', ftInteger);
Cds_NaMenu.IndexDefs.Add('Ordem', 'MN_TELA_CODIGO', []);
Cds_NaMenu.CreateDataSet;
Cds_NaMenu.LogChanges := False;
Cds_NaMenu.IndexName := 'Ordem';
我将数据放在TFDMemTable中,如下所示:
Cds_NaMenu.Append;
Cds_NaMenu.FieldByName('DISPONIBILIDADE').AsInteger := 1;
Cds_NaMenu.Post;
嗯......当set过滤属性为True并返回False时,问题就出现了。 RecordCount属性变为0;没有找到数据,即使我使用saveToFile程序。显然数据已经丢失。
_recCount := Cds_NaMenu.RecordCount; // Result = 867;
Cds_NaMenu.Filter := 'DISPONIBILIDADE=1 AND MN_MENU_PESQUISA like ' + QuotedStr('%' + sTexto + '%');
Cds_NaMenu.Filtered := True;
_recCount := Cds_NaMenu.RecordCount; // Result = 0;
Cds_NaMenu.Filtered := False;
Cds_NaMenu.Filter := '';
_recCount := Cds_NaMenu.RecordCount; // Result = 0;
PS:使用ClientDataSet,此代码可以正常运行
答案 0 :(得分:1)
如果您正在使用纯内存表,则RecordCount属性查询记录计数应该没有任何问题。在过滤值LIKE' %%' 时,您可能希望过滤后的视图中包含 NULL 和空值记录但事实并非如此。有这样的数据集:
ID | Value
1 | NULL
2 | ''
3 | 'Some text'
并应用这样的过滤器:
var
S: string;
begin
S := '';
FDMemTable.Filtered := False;
FDMemTable.Filter := 'Value LIKE ' + QuotedStr('%' + S + '%');
FDMemTable.Filtered := True;
{ ← FDMemTable.RecordCount should be 1 here for the above dataset }
end;
空和 NULL 值记录不应包含在视图中。这是一个简短的证据:
var
S: string;
MemTable: TFDMemTable;
begin
MemTable := TFDMemTable.Create(nil);
try
MemTable.FieldDefs.Add('ID', ftInteger);
MemTable.FieldDefs.Add('Value', ftString, 500);
MemTable.IndexDefs.Add('PK_ID', 'ID', [ixPrimary]);
MemTable.CreateDataSet;
MemTable.AppendRecord([1, NULL]);
MemTable.AppendRecord([2, '']);
MemTable.AppendRecord([3, 'Some text']);
S := '';
MemTable.Filtered := False;
MemTable.Filter := 'Value LIKE ' + QuotedStr('%' + S + '%');
ShowMessage(Format('Total count: %d', [MemTable.RecordCount])); { ← should be 3 }
MemTable.Filtered := True;
ShowMessage(Format('Filtered count: %d', [MemTable.RecordCount])); { ← should be 1 }
MemTable.Filtered := False;
ShowMessage(Format('Total count: %d', [MemTable.RecordCount])); { ← should be 3 }
finally
MemTable.Free;
end;
end;
答案 1 :(得分:0)
我认为这只是一个小小的FD怪癖。下面的代码按预期工作,Cds_NaMenu
被声明为TFDMemTable(尽管如果你可以删除Cds_
以避免混淆,那将会很好。)
我认为关键区别在于清除过滤器后调用.Locate
。我把它放在那里的原因是因为它导致数据集滚动,我想,重新计算其RecordCount
的结果。可能导致滚动的任何其他操作都会产生相同的效果,即使MoveBy(0)
- 尝试它。
procedure TForm1.FormCreate(Sender: TObject);
var
_recCount : Integer;
ID : Integer;
sTexto : String;
begin
sTexto := 'xxx'; // added
Cds_NaMenu.FieldDefs.Add('ID', ftInteger);
Cds_NaMenu.FieldDefs.Add('MN_TELA_CODIGO', ftInteger);
Cds_NaMenu.FieldDefs.Add('MN_MENU_PESQUISA', ftString, 500);
Cds_NaMenu.FieldDefs.Add('DISPONIBILIDADE', ftInteger);
Cds_NaMenu.IndexDefs.Add('Ordem', 'MN_TELA_CODIGO', []);
Cds_NaMenu.CreateDataSet;
Cds_NaMenu.LogChanges := False;
Cds_NaMenu.IndexName := 'Ordem';
Cds_NaMenu.Append;
Cds_NaMenu.FieldByName('ID').AsInteger := 666; // added
Cds_NaMenu.FieldByName('DISPONIBILIDADE').AsInteger := 1;
Cds_NaMenu.Post;
_recCount := Cds_NaMenu.RecordCount; // Result = 1
ID := Cds_NaMenu.FieldByName('ID').AsInteger; // added
Cds_NaMenu.Filter := 'DISPONIBILIDADE=1 AND MN_MENU_PESQUISA like ' + QuotedStr('%' + sTexto + '%');
Cds_NaMenu.Filtered := True;
_recCount := Cds_NaMenu.RecordCount; // Result = 0;
Cds_NaMenu.Filtered := False;
Cds_NaMenu.Filter := '';
// Now force the dataset to scroll
if Cds_NaMenu.Locate('ID', ID, []) then; // added
_recCount := Cds_NaMenu.RecordCount; // Result = 1;
Caption := IntToStr(_recCount); // added
end;