如果您坚持使用嵌套集，那么以下内容对您没有任何用处，但如果您愿意考虑使用邻接列表方法，则可能会感兴趣以下简单示例。
完整的脚本可以在这里找到：http: //pastie.org/1720133
我提供了 2 个存储过程。第一个采用 role_id 并输出授予该角色及其后代的权限列表：
mysql> call list_role_permissions(99); -- root role
+---------+---------+-----------+-----------------+
| role_id | perm_id | role_name | permission_name |
+---------+---------+-----------+-----------------+
| 99 | 5 | root | create forum |
| 3 | 4 | admin | move forum |
| 2 | 3 | moderator | edit post |
| 1 | 2 | member | create post |
| 0 | 1 | guest | view post |
+---------+---------+-----------+-----------------+
5 rows in set (0.00 sec)
mysql> call list_role_permissions(2); -- moderator role
+---------+---------+-----------+-----------------+
| role_id | perm_id | role_name | permission_name |
+---------+---------+-----------+-----------------+
| 2 | 3 | moderator | edit post |
| 1 | 2 | member | create post |
| 0 | 1 | guest | view post |
+---------+---------+-----------+-----------------+
3 rows in set (0.00 sec)
第二个接受 user_id 并输出授予该用户角色的权限列表：
mysql> call list_user_role_permissions(1); -- root user
+---------+---------+-----------+-----------------+
| role_id | perm_id | role_name | permission_name |
+---------+---------+-----------+-----------------+
| 99 | 5 | root | create forum |
| 3 | 4 | admin | move forum |
| 2 | 3 | moderator | edit post |
| 1 | 2 | member | create post |
| 0 | 1 | guest | view post |
+---------+---------+-----------+-----------------+
5 rows in set (0.00 sec)
mysql> call list_user_role_permissions(3); -- moderator user
+---------+---------+-----------+-----------------+
| role_id | perm_id | role_name | permission_name |
+---------+---------+-----------+-----------------+
| 2 | 3 | moderator | edit post |
| 1 | 2 | member | create post |
| 0 | 1 | guest | view post |
+---------+---------+-----------+-----------------+
3 rows in set (0.00 sec)
如果您担心邻接列表的性能，您可以使用我本月早些时候做的 500 万行 Yahoo GeoPlanet 示例检查此方法的结果：
从 MySQL 中的分层数据生成基于深度的树（无 CTE）
希望这会有所帮助（如果您卡在嵌套集路径上，请忽略）
求...
表
drop table if exists roles;
create table roles
(
role_id tinyint unsigned not null primary key,
name varchar(255) unique not null,
parent_role_id tinyint unsigned,
key (parent_role_id)
)engine=innodb;
drop table if exists users;
create table users
(
user_id int unsigned not null auto_increment primary key,
username varchar(32) unique not null
)engine=innodb;
drop table if exists user_roles;
create table user_roles
(
user_id int unsigned not null,
role_id tinyint unsigned not null,
primary key (user_id, role_id)
)engine=innodb;
drop table if exists permissions;
create table permissions
(
perm_id smallint unsigned not null auto_increment primary key,
name varchar(255) unique not null
)engine=innodb;
drop table if exists role_permissions;
create table role_permissions
(
role_id tinyint unsigned not null,
perm_id smallint unsigned not null,
primary key (role_id, perm_id)
)engine=innodb;
存储过程
drop procedure if exists list_role_permissions;
delimiter #
create procedure list_role_permissions
(
in p_role_id tinyint unsigned
)
proc_main:begin
declare done tinyint unsigned default 0;
declare dpth smallint unsigned default 0;
create temporary table hier(
parent_role_id tinyint unsigned,
role_id tinyint unsigned,
depth smallint unsigned default 0
)engine = memory;
/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */
insert into hier select parent_role_id, role_id, dpth from roles where role_id = p_role_id;
create temporary table tmp engine=memory select * from hier;
while not done do
if exists( select 1 from roles r inner join tmp on r.parent_role_id = tmp.role_id and tmp.depth = dpth) then
insert into hier select r.parent_role_id, r.role_id, dpth + 1 from roles r
inner join tmp on r.parent_role_id = tmp.role_id and tmp.depth = dpth;
set dpth = dpth+1;
truncate table tmp;
insert into tmp select * from hier where depth = dpth;
else
set done = 1;
end if;
end while;
select
rp.*,
r.name as role_name,
p.name as permission_name
from
role_permissions rp
inner join hier h on h.role_id = rp.role_id
inner join permissions p on rp.perm_id = p.perm_id
inner join roles r on rp.role_id = r.role_id
order by
rp.role_id desc;
drop temporary table if exists hier;
drop temporary table if exists tmp;
end proc_main #
delimiter ;
drop procedure if exists list_user_role_permissions;
delimiter #
create procedure list_user_role_permissions
(
in p_user_id int unsigned
)
proc_main:begin
declare done tinyint unsigned default 0;
declare dpth smallint unsigned default 0;
create temporary table hier(
parent_role_id tinyint unsigned,
role_id tinyint unsigned,
depth smallint unsigned default 0
)engine = memory;
/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */
insert into hier select r.parent_role_id, r.role_id, dpth from roles r
inner join user_roles ur on ur.user_id = p_user_id and ur.role_id = r.role_id;
create temporary table tmp engine=memory select * from hier;
while not done do
if exists( select 1 from roles r inner join tmp on r.parent_role_id = tmp.role_id and tmp.depth = dpth) then
insert into hier select r.parent_role_id, r.role_id, dpth + 1 from roles r
inner join tmp on r.parent_role_id = tmp.role_id and tmp.depth = dpth;
set dpth = dpth+1;
truncate table tmp;
insert into tmp select * from hier where depth = dpth;
else
set done = 1;
end if;
end while;
select distinct
rp.*,
r.name as role_name,
p.name as permission_name
from
role_permissions rp
inner join hier h on h.role_id = rp.role_id
inner join permissions p on rp.perm_id = p.perm_id
inner join roles r on rp.role_id = r.role_id
order by
rp.role_id desc;
drop temporary table if exists hier;
drop temporary table if exists tmp;
end proc_main #
delimiter ;
测试数据和测试
insert into roles values
(99,'root',null),
(3,'admin',99),
(2,'moderator',3),
(1,'member',2),
(0,'guest',1);
insert into users (username) values
('f00'),('bar'),('alpha'),('beta'),('gamma');
insert into user_roles values
(1,99), -- (1,1),
(2,3), -- (2,2),(2,1),
(3,2), -- (3,1),
(4,1),
(5,0);
insert into permissions (name) values
('view post'), ('create post'), ('edit post'), ('move forum'), ('create forum');
insert into role_permissions values
-- guest
(0,1),
-- member
(1,2),
-- moderator
(2,3),
-- admin
(3,4),
-- root
(99,5);
call list_role_permissions(99); -- root role
call list_role_permissions(3); -- admin role
call list_role_permissions(2); -- moderator role
call list_role_permissions(1); -- member role
call list_role_permissions(0); -- guest role
call list_user_role_permissions(1); -- root user
call list_user_role_permissions(2); -- admin user
call list_user_role_permissions(3); -- moderator user
call list_user_role_permissions(4); -- member user
call list_user_role_permissions(5); -- guest user