@RequestMapping("/test")

    public String execute() {

        /* 先创建一个example */

        GoodsExample goodsExample = new GoodsExample();

        /* 然后创建criteria对象 */

        GoodsExample.Criteria criteria = goodsExample.createCriteria();

        criteria.andCategoryIdIsNotNull();

        List<Goods> goodses = goodsMapper.selectByExample(goodsExample);

        System.out.println(goodses);

        return "dd";

    }

 select * from shop_user where id is not null;