SQL View union from joiner table

Question

I have the following situation and I am not sure how best to address it. Any guidance on how to prepare the needed view would be greatly appreciated.

I have 4 tables:
users (userid int, username varchar)
roles (roleid int, rolename varchar)
businessunit (buid int, buname varchar)
user_role_map (userid, roleid, buid)

In the roles table I have a role with the id of 0 which is the "system admin" role and in the businessunit table I have an IT business unit. Any users resulting from the below query would be considered system admins and should have full access to every business unit.

SELECT userid FROM user_role_map WHERE roleid = 0 AND buid = 0

I need to build a view that shows all "non system admins" union'd to a list of every business unit and every "system admin" user. The first part is easy with the below query, but the second part is what what I am struggling with.

SELECT userid, roleid, buid FROM user_role_map WHERE roleid > 0 AND buid > 0

I will give some example data to help illustrate what I am trying to accomplish:

users
---------------
1, "sysAdmin"  
2, "salesUser1"  
3, "serviceUser1"  
4, "manager1"  
5, "salesUser2"
6, "serviceUser2"
7, "manager2"

roles
---------------
0, "SystemAdmin"
1, "Full"
2, "Update"
3, "Read"

businessunit --------------- 0, "IT" 1, "fooSales" 2, "fooService" 3, "barSales" 4, "barService"

user_role_map
---------------
1, 0, 0
2, 1, 1
2, 3, 3
3, 1, 2
3, 3, 4
4, 1, 1
4, 1, 2
5, 1, 3
5, 3, 1
6, 1, 4
6, 3, 3
7, 1, 2
7, 1, 4

Finally, i need the view to provide the following for the above sample data (note the last 4 rows):

new view
---------------
2, 1, 1
2, 3, 3
3, 1, 2
3, 3, 4
4, 1, 1
4, 1, 2
5, 1, 3
5, 3, 1
6, 1, 4
6, 3, 3
7, 1, 2
7, 1, 4
1, 1, 1
1, 1, 2
1, 1, 3
1, 1, 4

NOTE: the example data here only has one "System Admin" user but there could be any number of users of this type.

Answer 1

You should be able to do something like this:

declare @users table(userid int, username varchar(255));
insert into @users values (1, 'sysAdmin');
insert into @users values (2, 'salesUser1');  
insert into @users values (3, 'serviceUser1');  
insert into @users values (4, 'manager1');  
insert into @users values (5, 'salesUser2');
insert into @users values (6, 'serviceUser2');
insert into @users values (7, 'manager2');


declare @roles table(roleid int, rolename varchar(255));
INSERT INTO @roles VALUES (0, 'SystemAdmin');
INSERT INTO @roles VALUES (1, 'Full');
INSERT INTO @roles VALUES (2, 'Update');
INSERT INTO @roles VALUES (3, 'Read');

DECLARE @user_role_map TABLE(userid INT, roleid INT, buid int)
INSERT INTO @user_role_map values (1, 0, 0);
INSERT INTO @user_role_map values (2, 1, 1);
INSERT INTO @user_role_map values (2, 3, 3);
INSERT INTO @user_role_map values (3, 1, 2);
INSERT INTO @user_role_map values (3, 3, 4);
INSERT INTO @user_role_map values (4, 1, 1);
INSERT INTO @user_role_map values (4, 1, 2);
INSERT INTO @user_role_map values (5, 1, 3);
INSERT INTO @user_role_map values (5, 3, 1);
INSERT INTO @user_role_map values (6, 1, 4);
INSERT INTO @user_role_map values (6, 3, 3);
INSERT INTO @user_role_map values (7, 1, 2);
INSERT INTO @user_role_map values (7, 1, 4);

DECLARE @businessunit TABLE(buid int, buidname VARCHAR(255));
INSERT INTO @businessunit VALUES (0, 'IT')
INSERT INTO @businessunit VALUES (1, 'fooSales')
INSERT INTO @businessunit VALUES (2, 'fooService')
INSERT INTO @businessunit VALUES (3, 'barSales')
INSERT INTO @businessunit VALUES (4, 'barService')

--non-admin users
SELECT userid, roleid, buid 
FROM @user_role_map 
WHERE 
    roleid > 0 AND buid > 0

UNION ALL

--get admin users and add a full control entry
SELECT userid, 1, BusinessUnits.buid 
FROM @user_role_map m
CROSS JOIN(
    --use this if you have a businessunit table you can leverage; otherwise, 
    --you can select distinct buid on role_map where  buid > 0
    SELECT buid
    FROM @businessunit
    WHERE buid > 0
) AS BusinessUnits
WHERE 
    roleid = 0 AND m.buid = 0

Answer 2

You could append the business unit's with a UNION ALL to your view.

SELECT 
    userid, 
    roleid, 
    buid 
FROM 
    user_role_map 
WHERE 
    roleid > 0 
  AND buid > 0

UNION ALL

/* append full control for system admins to all bussiness units */

SELECT 
    CAST(1 AS INT) AS userid, 
    CAST(1 as INT) AS roleid, 
    BU.buid 
FROM businessunit BU