网上有相关的例子，楼主可以找找看，这些都是基本的东西。随便找了几段仅供参考Delphi(Pascal) code

unit AddUse;

interface

uses
windows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,
Dialogs,StdCtrls,Buttons,ExtCtrls,DB,DBTables,ADODB;

type
TAddUseForm=class(TForm)
Bevel1:TBevel;
Label1:TLabel;
Label2:TLabel;
Label3:TLabel;
NewName:TEdit;
Password:TEdit;
NPassword:TEdit;
Add_ok:TBitBtn;
Add_cancel:TBitBtn;
RadioGroup1:TRadioGroup;
J0:TRadioButton;
J1:TRadioButton;
DataSource1:TDataSource;
Panel1:TPanel;
ADOTable1:TADOTable;
procedure Add_cancelClick(Sender:TObject);
procedure Add_okClick(Sender:TObject);
procedure FormCreate(Sender:TObject);
private
{ Private declarations }
public
function FindName(const Name:string):Boolean;
{ Public declarations }
end;

var
AddUseForm:TAddUseForm;

implementation
uses DataM;
{$R *.dfm}

procedure TAddUseForm.Add_cancelClick(Sender:TObject);
begin
Close;
end;

procedure TAddUseForm.Add_okClick(Sender:TObject);
var
rec:string;
begin
if NewName.Text=” then
begin
application.MessageBox(PChar(‘用户名不能为空！’),’警告’,mb_iconexclamation);
NewName.SetFocus;
exit;
end;

if FindName(NewName.Text) then
begin
application.MessageBox(PChar(‘用户名:"’+NewName.Text+’"已存在！’),’提示’,mb_iconexclamation);
NewName.SetFocus;
end
else
begin
if Password.Text<>NPassword.Text then
begin
application.MessageBox(PChar(‘"验证密码"与"密码"不相同！（请注意大小写！）’),’错误’,mb_iconstop);
NPassword.SetFocus;
exit;
end;
ADOTable1.Append;
ADOTable1.FieldByName(‘用户名’).AsString:=NewName.Text;
if Password.Text=” then
Password.Text:=’ ‘;
ADOTable1.FieldByName(‘密码’).AsString:=Password.Text;
if J0.Checked then
rec:=’管理级’
else
rec:=’普通级’;
ADOTable1.FieldByName(‘级别’).AsString:=rec;
ADOTable1.Post;
if application.MessageBox(PChar(‘"’+NewName.Text+’"添加成功！是否继续添加？’),
‘提示’,mb_yesno+mb_iconquestion)=idyes then
begin
NewName.Text:=”;
Password.Text:=”;
NPassword.Text:=”;
NewName.SetFocus;
end
else
Close;
end;
end;

function TAddUseForm.FindName(const Name:string):Boolean;
begin
Result:=false;
ADOTable1.First;
while not ADOTable1.Eof do
begin
if ADOTable1.FieldByName(‘用户名’).AsString=NewName.Text then
begin
Result:=true;
exit;
end;
ADOTable1.Next;
end;
end;

procedure TAddUseForm.FormCreate(Sender:TObject);
begin
ADOTable1.Open;
end;

end.