QueryWrapper<Source> queryWrapper = new QueryWrapper();
		if (StrUtil.isNotEmpty(filter)) {
			queryWrapper.or(i->i.like("name", filter).or().like("description", filter));
		}
		if (StrUtil.isNotEmpty(catalog)) {
			queryWrapper.eq("catalog_id", catalog);
		}

//根据id查询
        User user = userMapper.selectById(1);
        System.out.println("根据id查询" + user);
 
        //普通查询
        System.out.println("----- 普通查询 ------");
        List<User> plainUsers = userMapper.selectList(new QueryWrapper<User>().eq("role_id", 2L).orderByAsc("age"));
        List<User> lambdaUsers = userMapper.selectList(new QueryWrapper<User>().lambda().eq(User::getRoleId, 2L));
        System.out.println("查询默认未删除 deleted=0" + plainUsers);
 
 
 
        //子查询
        System.out.println("----- 子查询 ------");
        List<User> plainUsers2 = userMapper.selectList(new QueryWrapper<User>()
                .inSql("role_id", "select id from role where id = 2"));
        System.out.println("子查询"+plainUsers2);
        List<User> lambdaUsers2 = userMapper.selectList(new QueryWrapper<User>().lambda()
                .inSql(User::getRoleId, "select id from role where id = 2"));
        System.out.println("子查询"+lambdaUsers2);
 
 
 
 
        //带嵌套查询
        System.out.println("----- 带嵌套查询 ------");
        List<User> plainUsers3 = userMapper.selectList(new QueryWrapper<User>()
                .nested(i -> i.eq("role_id", 2L).or().eq("role_id", 3L))
                .and(i -> i.ge("age", 20)
                ));
        List<User> lambdaUsers3 = userMapper.selectList(new QueryWrapper<User>().lambda()
                .nested(i -> i.eq(User::getRoleId, 2L).or().eq(User::getRoleId, 3L))
                .and(i -> i.ge(User::getAge, 20)));
        System.out.println("带嵌套查询"+plainUsers3);
        System.out.println("带嵌套查询"+lambdaUsers3);
 
        //自定义(sql注入)
        System.out.println("----- 自定义(sql注入) ------");
        List<User> plainUsers4 = userMapper.selectList(new QueryWrapper<User>()
                .apply("role_id = 2"));