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我遇到这样的事情，就是在访问数据库的时候，有时需要把当前的这个记录的位置保存下来，因为在后来的访问操作中，我有可能要回到这一个保存点，该怎么实现？是不是用Bookmark?怎么用？
看看下面的代码，也许对你有帮助·
This example uses a button to copy the value of a field in the previous record into the corresponding field in the current record.
procedure TForm1.CopyDataClick(Sender: TObject);
var
SavePlace: TBookmark;
PrevValue: Variant;
begin
with Table1 do
begin
{ get a bookmark so that we can return to the same record }
SavePlace := GetBookmark;
{ move to prior record}
FindPrior;
{ get the value }
PrevValue := Fields[0].Value;
{Move back to the bookmark
this may not be the next record anymore
if something else is changing the dataset asynchronously }
GotoBookmark(SavePlace);
{ Set the value }
Fields[0].Value := PrevValue;
{ Free the bookmark }
FreeBookmark(SavePlace);
end;
end;
To ensure that the button is disabled when there is no previous record, the OnDataChange event of the DataSource detects when the user moves to the beginning of file (BOF property becomes True), and disables the button.
procedure TForm1.Table1DataChange(Sender: TObject; Field: TField);
begin
if Table1.BOF then
CopyData.Enabled := False
else
CopyData.Enabled := True;
end;
是的,如下:
var
SavePlace: TBookmark;//要定义一个用于保存这个点的变量
PrevValue: Variant;
begin
withClientDataSet1 do
begin
SavePlace := GetBookmark;
try
.......................
GotoBookmark(SavePlace);//回到原来的记录
finally
FreeBookmark(SavePlace);//释放这个变量
end;
end;
