小编dan*_*nte的帖子

我试图从两个选择语句中插入两个值，例如：

INSERT INTO manytomany_relation_a_and_b_tables (a_id, b_id) VALUES 
(SELECT id FROM a_table WHERE someColumnFromA="SOMETHING"), 
(SELECT id FROM b_table WHERE someColumnFromB="SOMETHING");

显然是不行的，但是怎样才能达到我想要的效果呢？

我正在尝试为访客和用户执行某些操作,并且我做了一些事情,但它不起作用,标题中出现错误.

/ home和/ logged/home使用相同的jsp

我希望为了"注册"而不会为已登录的用户显示"登录"

MainController:

@Controller  
public class MainController {

DBConnection db = new DBConnection();

@RequestMapping(value = "/home.html", method = RequestMethod.GET)
public ModelAndView HomePage(@RequestParam boolean guest) {

    User user = new User();
    user.setGuest(guest);
    user.isGuest();

    ModelAndView main = new ModelAndView("Main");

    return main;

}

@RequestMapping(value = "/logged/home.html", method = RequestMethod.GET)
public ModelAndView homePageforUsers(@RequestParam boolean loggeduser) {

    User user = new User();
    user.setUser(loggeduser);
    user.isUser();

    ModelAndView main = new ModelAndView("Main");

    return main;

}

main.jsp中:

<c:if test="${user.isUser()}">
<div class="cart">
<a href="http://localhost:8080/OnlineShop/cart.html"
        style="text-decoration: none; color: …