create table role
(
role_id int primary key
)

create table groups
(
groups_id int primary key,
role_id int not null,
FOREIGN KEY (role_id) REFERENCES  role(role_id),
UNIQUE(groups_id,role_id)
)

create table usres
(
usres_id int primary key,
role_id int not null,
FOREIGN KEY (role_id) REFERENCES role(role_id),
UNIQUE(usres_id, role_id)
)

create table usres_group
(
usres_id int not null,
groups_id int not null,
role_id int not null,
primary key (usres_id, groups_id)
)

alter table usres_group add CONSTRAINT usres_group_groups FOREIGN KEY (groups_id, role_id) REFERENCES groups(groups_id, role_id)
ALTER TABLE dbo.usres_group ADD CONSTRAINT usres_group_usres FOREIGN KEY (usres_id, role_id) REFERENCES dbo.usres(usres_id, role_id)