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Delphi控件的使用经验(3) begin
LongID:=DelList.Strings[0];
DelList.Delete(0);
Table1.SetKey;
Table1.FieldByName(′LongID′).AsString:=LongID;
if Table1.GotoKey then Table1.Delete;
if HasSubInDbf(TreeView1.Selected) then
begin
NSubLongID:=Table1.FieldByName(′LongID′).AsString;
while (copy(NSubLongID,1,3)=copy
(LongID,4,3))and(not Table1.Eof) do
begin
dellist.Add(NSubLongId);
Table1.Next;
NSubLongId:=Table1.FieldByName(′LongID′).AsString;
end;
end;
end;
DelList.Free;
TreeView1.Items.Delete(TreeView1.Selected);
end;
为TreeView1的OnEXPanding事件添加代码：
procedure TForm1.TreeView1EXPanding
(Sender: TObject; Node: TTreeNode;
var AllowEXPansion: Boolean);
var TmpNode:TTreeNode;NSubLongID:
String;p:Pstr;bm:TBookMark;
begin
with Table1,TreeView1 do
begin
Items.BeginUpdate;
SetKey;
FieldByName(′LongID′).AsString:=Pstr(Node.Data)^;
if not GotoKey then Items.Delete(Node)
else
begin
TmpNode:=Node.GetFirstChild;
if (TmpNode.Text=′ ′)and(TmpNode.Data=nil) then
begin
TmpNode.Delete;
if HasSubInDbf(Node) then
begin
NSubLongID:=FieldByName(′LongID′).AsString;
while (copy(NSubLongID,1,3)=copy(Pstr
(Node.Data)^,4,3))and(not Eof) do
begin
new(p);
p^:=FieldByName(′LongID′).AsString;
bm:=GetBookMark;
TmpNode:=Items.AddChildObject(Node,
FieldByName(′Text′).AsString,p);
if HasSubInDbf(TmpNode) then Items.
AddChildObject(TmpNode,′ ′,nil);
GotoBookMark(bm);
FreeBookMark(bm);
Next;
NSubLongId:=FieldByName(′LongID′).AsString;
end; end; end;
end;
Items.EndUpdate;
end;
end;
---- 以上简要谈了谈数据库的树状显示的基本方法，另外，编辑树上节点的Text属性的同时对数据库进行修改、同一数据库在多用户同时操作时数据库以及树的一致性、树上节点的拷贝与复制等就不再赘述，读者可自行完善。
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