15.2.3 TSession部件應用舉例
例15.1：我們創建一個應用程序，通過調用TSession有關的方法獲取當前應用程序可以進行連接的數據庫的名字以及獲取其中任意一個數據庫中的全部數據庫表的名字。
通過TSession部件獲取數據庫的有關信息
窗體中主要使用了兩個列表框，其中列表框DatabaselistBox用於顯示數據庫的名字，列表框TablelistBox用於顯示數據庫中的表名。程序運行完後數據庫的名字顯示在DatabaselistBox列表框中，當用戶單擊DatabaselistBox列表框中的數據庫名時，該數據庫全部的數據庫表的名字將會顯示在TablelistBox列表框中。有關的程序代碼如下：
程序清單15.1
unit unit31;
interface
uses
SysUtils, Windows, Messages, Classes, Graphics, Controls,
Forms, Dialogs, StdCtrls, DB, DBTables, Buttons, ComCtrls, Tabnotbk;
type
TQueryForm = class(TForm)
BitBtn1: TBitBtn;
DataSource1: TDataSource;
Table1: TTable;
GroupBox1: TGroupBox;
CheckBox1: TCheckBox;
CheckBox2: TCheckBox;
PageControl1: TPageControl;
TabSheet1: TTabSheet;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
ListBox1: TListBox;
ListBox2: TListBox;
ListBox3: TListBox;
TabSheet2: TTabSheet;
Memo1: TMemo;
procedure FormCreate(Sender: TObject);
procedure ListBox1Click(Sender: TObject);
procedure ListBox2Click(Sender: TObject);
end;
var
QueryForm: TQueryForm;
implementation
{$R *.DFM}
uses RSLTFORM;
procedure TQueryForm.FormCreate(Sender: TObject);
begin
Screen.Cursor := crHourglass;
{ Populate the alias list }
with ListBox1 do
begin
Items.Clear;
Session.GetAliasNames(Items);
end;
{ Make sure there are aliases defined }
Screen.Cursor := crDefault;
if ListBox1.Items.Count < 1 then
MessageDlg( 'There are no database aliases currently defined. You ' +
'need at least one alias to use this demonstration.',
mtError, [mbOK], 0 );
end;
procedure TQueryForm.ListBox1Click(Sender: TObject);
var
strValue: string; { Holds the alias selected by the user }
bIsLocal: Boolean; { Indicates whether or not an alias is local }
slParams: TStringList; { Holds the parameters of the selected alias }
iCounter: Integer; { An integer counter variable for loops}
begin
{ Determine the alias name selected by the user }
with ListBox1 do
strValue := Items.Strings[ItemIndex];
{ Get the names of the tables in the alias and put them in the
appropriate list box, making sure the user's choices are reflected
in the list. }
ListBox2.Items.Clear;
Session.GetTableNames(strValue, { alias to enumerate }
'', { pattern to match }
