I'd like to assign a primary role to a user with many roles and I'm wondering what method is preferable, if any. Either to make a primary_role_id column in the users table or add an is_primary column in the pivot table:
Users:
id
name
primary_role_id here?
1
alice
2
2
bob
1
Roles:
id
name
1
super
2
admin
Role User:
user_id
role_id
OR is_primary here?
1
1
true
1
2
false
2
1
false
2
2
true
Requirement
It is simple, but not quite that simple. What you really want is:
each User is permitted 1-to-n Roles
of that set, one RoleUser is primary
Therefore:
the IsPrimary indicator has to be in RoleUser
you need a CHECK Constraint on RoleUser, that calls a Function, to ensure that there is just 1 IsPrimary Role per User.
That is an ordinary capability in Standard SQL, available in genuine SQL Platforms, not possible in the freeware.
Requirement is Not
each User is permitted 1-to-n Roles
each User has 1 primary Role
which leads to maintenance complexity: the set is in one place, the indicator for the set in another. The Function required checks that the User has the Role in RoleUser that is declared as PrimaryRoleId.
which is inferior and incorrect
the "User has one-to-one PrimaryRole" is true as a result, but not as a declarative.
Related
I have slightly complex relation going on my Rails application that I'm having a lot of trouble with.
For starters, there's a table that contains a list of roles which have an id and a priority. An example table looks like this
id priority
1 5
2 4
5 3
6 2
7 1
Now there's also a join_table that likes user ids with role ids in order to keep track of which user is assigned which role. The complicated part is that a user can have many roles
user_id role_id
3 1
3 2
3 7
4 1
4 5
4 6
What I'm trying to get is to filter done the users_roles table to only 1 entry per user based on the role with the lowest priority.
So what I'm trying to end up with is:
user_id role_id
3 7
4 6
The reason I would end up with this is due to the fact that roles 7 and 6 have the lowest priority.
Any help would be much appreciated
I'm pretty sure I might have solved this my self. The query I'm using is:
SELECT user_id, role_id, min(roles.priority)
FROM users_roles INNER JOIN roles
ON users_roles.role_id = roles.id
GROUP BY user_id
I have User table which contains same user represented by different entities all around. For example
User Table
==========================
id name
1 John Doe
2 Doe, John
3 Nicholas Cage
4 BlackRiderXXX
5 Nicholas cage
where users John Doe, Doe, John, BlackRiderXXX are the same people. Also, Nicholas Cage and Nicholas cage are the same people. Other tables refer to user.id randomly based on which user object did the action.
For Action table it'll look like
Action Table
==========================
id user_id some_other_stuff
1 1 ...
2 2 ...
3 1 ...
4 4 ...
5 3 ...
Where the actions 1,2,3,4 are all done by John Doe.
I'll have these users merged by the user manually meaning we'd know who is whom. They'd also select which User is the one they'd like to be as their main user account so we need to know this information as well.
I'm simplifiying a bit but I have a dozen tables which are like the Action table I provided above. We have mainly two use cases on how we will need to query:
1) Find actions which are done by user X (which should check all the users entities belonging to user X)
2) Find actions and group unique users
Main point is we will be using it everywhere around the codebase on 100+ queries so we want to design it well. How can I construct a system where the query will be simple enough also powerful enough to handle different querying ways?
Thanks
PS: We are using PostgreSQL
Why not include the "main" user in the first table?
User Table
id name main_user_id
1 John Doe 1
2 Doe, John 1
3 Nicholas Cage 2
4 BlackRiderXXX 1
5 Nicholas cage 2
Then you would join on:
select . . .
from actions a join
users u
on a.user_id = u.id
where u.main_user_id = 1;
If you want this selectable per end user, then use a different table:
create table end_user_users (
end_user_users_id serial primary key,
end_user_id int references end_users (end_user_id),
end_user_user_id int references users (id),
end_user_main_user_id int references users (id)
);
Then the query would look like:
select . . .
from actions a join
end_users_users euu
on euu.end_user_user_id = a.user_id and
euu.end_user_id = $my_id
where euu.end_user_main_user_id = 1;
You can use regexp_replace(),initcap() and trim() functions to refine and extract the common name strings to be grouped, and then generate values for newly created action_id column depending on them :
with new_action0 as
(
select u.id as id,
case when strpos(u.name,',') > 0 then
initcap(trim(regexp_replace(trim(u.name),'(.*),(.*)','\2 \1')))
else
case when lower(trim(u.name))='blackriderxxx' then
'John Doe'
else
trim(initcap(u.name))
end
end as name
from action u
)
select n.id, dense_rank() over (order by n.name) as user_id
from new_action0 n;
Demo
A new decent user table can be created by using this query with create table .. as statement
I currently have a single table that hosts all of my users. Now some users have team_leaders which reference the user id of the team leader which is also stored in the database.
Now, what I wanted to do do (and can't figure out) is how to query the database where it retrieves a list of the ids of all the team members and the leader in one result set.
For Example
name | id | team_leader
--------------------------------------------------
Jack | 1 | null
--------------------------------------------------
Susan| 2 | 1
--------------------------------------------------
Bob | 3 | 1
--------------------------------------------------
Eric | 4 | null
--------------------------------------------------
SELECT name FROM users where team_leader = '<some user's id>'
returns [ 'Susan', Bob']
But I would like it to return the team leader included, such as
['Jack', 'Susan', 'Bob']
Does anyone have any idea how to include the team leader in the query results?
EDIT:
Okay, so it seems like I have not explained myself 100%, my apologies. so the goal of this query is to do as follows.
I have another table called leads and there is a field there that is called user_id which correlates to the user that has access to the lead. Now, I want to introduce the ability for team leaders to update the leads that are associated with their accounts, so if the current user is a team leader they should have the ability to update the user_id from their id to anyone on their team, from one of their children to another, and from one of the children to themselves, but not to anyone not on their team. So the way I thought of it was to have a WHERE EXISTS or a WHERE IN (this would mean adding a field to the lead table called leader_id) and it checks if the new user_id is in a list of that team leader's members, including themselves.
Based off the example above.
UPDATE lead SET user_id = xxx
WHERE lead.id = yyy
AND ...
-- here is where I would check that the user_id xxx is part of the current
-- user's team which must be a team leader, for example user.id = 1
So my thought process was to get the previous query to then check against.
Hope this clears things up.
If I'm understanding correctly, you can just use or:
select name
from users
where team_leader = 1 or id = 1
WITH CTE AS(
SELECT name,id,team_leader FROM [users]
WHERE team_leader=1
UNION ALL
SELECT u.name,u.id,u.team_leader from [users] u
JOIN CTE ON CTE.empno=u.team_leader`enter code here`
and u.team_leader=1
)
SELECT * FROM CTE
I have two tables in my sql:
Users :
id name roleid
1 David 1
2 Sean 2
3 Joe 1
Roles:
roleid desc
1 copy
2 delete
3 move
Now i use this cmd to select the user with the user permission
SELECT * FROM Users u INNER JOIN Roles r ON u.roleid = r.roleid
Now i want to know if it's possible to build SQL Table(Roles Table), that it's will be dynamically the number of roleid for each user. something like:
Users :
id name roleid roleid2 roleid3
1 David 1 2 3
2 Sean 2
3 Joe 1 3
Use an associative entity to address the many-to-many relationship between Users and Roles. A composite primary key in the UserRole table will prevent duplicate assignment of roles, and foreign keys referencing the Users and Roles table will preserve referential integrity.
See SQL fiddle for a sample implementation.
At first, I suggest you to use many to many relationship. It means trird table: UsersRoles (userid,roleid)
At second, it's impossible create dynamic number of columns in typical SQL statement. But its possible by using stored procedures.
here is working example
sqlfiddle
I have a table called auctions, which has various columns such as username, auction id(the primary key), firstname, lastname, location etc, as well as a category column. The category column is blank by default, unless it is filled in for a particular record by a user.
I have made a new users table, which has username and category columns, as well as aditional fields which will be completed by user input.
I would like to know if it is possible when updating a record in the auctions table to have a category, to insert the username and category from that record into the users table as long as the username is not already present in the table.
For example, if I have the following tables:
auctions
auctionid username firstname lastname category
------------------------------------------------------------------------
1 zerocool john henry
2 fredflint fred smith
3 azazal mike cutter
Then, upon updating the second record to have a catagory like so:
2 fredflintsoner fred smith shoes
The resulting users table should be:
users
username shoes pants belts misc1 misc2
--------------------------------------------------
fredflint true
With no record have existed previously.
If additional auctions exist with the same username in the auctions table, such as:
7 fredflint fred smith belts
Then even if this auction is added to the category, a new record should not be inserted for the users table, as the username is already , however it should be updated as necessary, resulting in:
username shoes pants belts misc1 misc2
--------------------------------------------------
fredflint true true
What you are looking for is known as a TRIGGER. You can specify something to run after every insert/update in the auctions table and then determine what to do to the users table.
A couple of questions come to mind. The first is, your user table looks denormalized. What happens when you add a new category? Consider a user table in the form of:
id username category
Where you have multiple rows if a user has multiple categories:
1 fredflint shoes
2 fredflint pants
....
The second question I have is, why do you need a user table at all? It looks like all the information in the user table is already stored in the auction table! You can retrieve the user table simply by:
select distinct username, category
from auctions
If you need the separate table, an option to manually update the table when you create a new auction. I'd do it like this (I know just enough about triggers to avoid them):
1 - Make sure there's a row for this user
if not exists (select * from users where username = 'fredflint')
insert into users (username) values ('fredflint')
2 - Make sure he the shoe category
if not exists (select * from users where username = 'fredflint' and shoes = 1)
update users set shoes = 1 where username = 'fredflint'