Inno安装程序能否对新安装和更新做出不同的响应?

是的,使用脚本很容易。

只写

[Run]
Filename: "http://example.com"; Flags: shellexec; Check: NotAnUpdate

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurPageID = wpInstalling then
    IsUpdate := FileExists(ExpandConstant('{app}\TheFileNameOfMyApp.exe'));
end;

function NotAnUpdate: Boolean;
begin
  result := not IsUpdate;
end;

The answer by @AndreasRejbrand 如果用户选择将可执行文件安装到与上次不同的位置,将无法工作。

您可以查询特定于安装程序的Inno安装注册表项:

#define AppId "your-app-id"
#define SetupReg "Software\Microsoft\Windows\CurrentVersion\Uninstall\" + AppId + "_is1"
#define SetupAppPathReg "Inno Setup: App Path"

[Setup]
AppId={#AppId}
...

[Run]
Filename: "https://www.example.com/"; Flags: shellexec; Check: not IsUpgrade
...

[Code]

function IsUpgrade: Boolean;
var
  S: string;
begin
  Result :=
    RegQueryStringValue(HKLM, '{#SetupReg}', '{#SetupAppPathReg}', S) or
    RegQueryStringValue(HKCU, '{#SetupReg}', '{#SetupAppPathReg}', S);
end;

例如如何使用 IsUpgrade 在里面 [Code] 截面,见
Excludes part of Code section if installation is update in Inno Setup

检查这是您的“appid”包含左花括号:
Checking if installation is fresh or upgrade does not work when AppId contains a curly bracket