SQLite3 读写 TreeView！

最新推荐文章于 2025-03-04 15:50:20 发布

原创最新推荐文章于 2025-03-04 15:50:20 发布 · 688 阅读

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CC 4.0 BY-SA版权

文章标签：

#sqlite #integer #imagelist #button #string #数据库

这篇博客介绍了如何使用SQLite3数据库中的数据构建并显示在TreeView组件上。通过读取DataTable表，根据Parent字段来确定节点的层级关系，实现数据的树形结构展示。

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unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, fcTreeView,SQLiteTable3, StdCtrls, ImgList, ComCtrls;

type
TPItem = Record //表中记录的类型
Sign:Integer;
Caption:string;
Parent:Integer;

end;

PItem = ^TPItem; //指向极开路的指针

TForm1 = class(TForm)
fcTreeView2: TfcTreeView;
fcTreeView1: TfcTreeView;
ImageList1: TImageList;
Button1: TButton;
Button4: TButton;
function FindParentNode(Id:Integer):TfcTreeNode;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
slDBpath: string;
sldb: TSQLiteDatabase;
sltb: TSQLIteTable;
sSQL: String;
Node :TfcTreeNode;

Nodes:TfcTreeNodes;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
slDBPath := ExtractFilepath(Application.exename)+ 'ReadAndWrite.db';
sldb := TSQLiteDatabase.Create(slDBPath);
try //ID ，Caption 为节点的内容， parent 为父节点的编号， Next 为同级下一个节点的编号
if not sldb.TableExists('DataTable') then // DtaTable数据库中的表
begin
sSQL := 'CREATE TABLE DataTable ([ID] INTEGER PRIMARY KEY AUTOINCREMENT,[Sign] INTEGER NULL,[Caption] VARCHAR(255),'
+'[Parent] INTEGER NULL);';
sldb.execsql(sSQL);
end;
Except
exit;
end;
end;

//保存节点到数据库中！
procedure TForm1.Button1Click(Sender: TObject);
var
I:Integer;
PI:PItem;
Record1:TPItem;
begin
slDBPath := ExtractFilepath(Application.exename)+ 'ReadAndWrite.db';
sldb := TSQLiteDatabase.Create(slDBPath);
sldb.BeginTransaction;
for I := 0 to fcTreeView2.Items.Count-1 do
begin
Record1.Sign:= I ;
fcTreeView2.Items.Item[I].StringData := IntToStr(I);
Record1.Caption := fcTreeView2.Items.Item[I].Text;
if fcTreeView2.Items.Item[I].Parent <> nil then
Record1.Parent := StrToInt(fcTreeView2.Items.Item[I].Parent.StringData)
else
Record1.Parent := -1;
PI := @Record1;
sSQL := 'INSERT INTO DataTable(Sign,Caption,Parent)VALUES('
+IntToStr(PI.Sign)+',"'
+PI.Caption+'",'
+IntToStr(PI.Parent)+');';
sldb.ExecSQL(utf8encode(sSQL));
end;
sldb.Commit;

end;

//找父节点

function TForm1.FindParentNode(Id:Integer):TfcTreeNode;
var
I:Integer;
begin
Result := nil;
for i := 0 to fcTreeView1.Items.Count - 1 do
begin
if Integer(fcTreeView1.Items.Item[I].Data) = id then
begin
Result := fcTreeView1.Items[I];
Break;
end;
end;

end;

//读取数据库构造树

procedure TForm1.Button2Click(Sender: TObject);

begin

try
fcTreeView1.Items.BeginUpdate;
fcTreeView1.Items.Clear;
sltb :=slDb.GetTable('SELECT *FROM DataTable Order By Parent');
while not sltb.EOF do
begin
if sltb.FieldAsInteger(sltb.FieldIndex['Parent'])= -1 then
begin
fcTreeView1.Items.AddObject(nil,sltb.FieldAsString(sltb.FieldIndex['Caption']),Pointer(sltb.FieldAsInteger(sltb.FieldIndex['Sign'])));
end
else
begin
Node := FindParentNode(sltb.FieldAsInteger(sltb.FieldIndex['Parent']));
if Node <> nil then
begin
fcTreeView1.Items.AddChildObject(Node,sltb.FieldAsString(sltb.FieldIndex['Caption']),Pointer(sltb.FieldAsInteger(sltb.FieldIndex['Sign'])));
end;
end;
sltb.Next;
end;
finally
sltb.Free;
fcTreeview1.Items.EndUpdate;
end;