如何限制视图以仅显示单行类型而不限制行

Question

我有一个MySQL视图，其数据结构如下：

/==========================================\
| row_id | user_id | page_id | permissions |
|========|=========|=========|=============|
| 1      | 1       | test1   | 011         |
| 2      | 2       | test1   | 111         |
| 3      | 2       | test2   | 111         |
| 4      | 2       | test3   | 111         |
| 5      | 3       | test2   | 001         |
\==========================================/

问题是我真的只希望有人要求最多1个用户ID的数据。用户ID可能只有1行与之关联，或者可能有数百行。

我的问题：如何将视图限制为仅显示单个用户ID的数据？

实际视图SQL :(由PHPMyAdmin生成）

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";

CREATE ALGORITHM=MERGE DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `endpoint_permission_sets` AS
    SELECT
        `u`.`user_id` AS `user_id`,
        `p`.`id` AS `permission_id`,
        `p`.`endpoint` AS `endpoint`,
        `p`.`individual_permissions` AS `individual_permissions`,
        `p`.`collection_permissions` AS `collection_permissions`,
        `p`.`global_permissions` AS `global_permissions`
    FROM (
        (
            `other_schema`.`users` `u`
            LEFT JOIN `endpoint_groups` `g`
                ON (((`u`.`endpoint_group_id` = `g`.`id`) AND (`g`.`is_active` = 1)))
        )
        LEFT JOIN `endpoint_permissions` `p`
            ON ((
                ((`g`.`id` = `p`.`group_id`) OR (`u`.`user_id` = `p`.`user_id`))
                AND (`p`.`is_active` = 1)
            ))
    );