insert foreach x where not exists

Question

I have a fairly simple database consisting of three (relevant) tables: users, permissions, and user permissions. The basic premise is simple: when a user gets created, all the records in the permissions table are automatically added to the user_permissions table with a default value. This is all working fine.

However, as I'm currently in development, I continue to add new permissions, which of course existing users won't have since those new permissions didn't exist in the permissions table when they were created. So, I had the brilliant idea to create a little stored procedure to automatically update the user_permissions table with all the permissions not currently existing in the user_permissions table.

So, in short, what I want to do is something like (pseudocode)

For each user without x permission in user_permissions, insert into user_permissions user_id and permission_id

I wasn't quite sure how to do this from an SQL POV. I played with joins and "not exists" but haven't really gotten anywhere.

You can play with my schema here: http://sqlfiddle.com/#!3/b0761/3 Thanks in advance for the help!

EDIT: Schema:

CREATE TABLE users (
  user_id      int IDENTITY(1, 1) NOT NULL,
  user_name    varchar(255),
  PRIMARY KEY (user_id));

CREATE TABLE permissions (
  permission_id          int IDENTITY(1, 1) NOT NULL, 
  permission_name        varchar(255) NOT NULL, 
  PRIMARY KEY (permission_id));

CREATE TABLE user_permissions (
  user_id       int NOT NULL, 
  permission_id int NOT NULL, 
  value         tinyint DEFAULT 0 NOT NULL,  
  PRIMARY KEY (user_id, 
  permission_id));

ALTER TABLE user_permissions ADD CONSTRAINT FK_user_pe338140 
FOREIGN KEY (permission_id)
REFERENCES permissions (permission_id);

ALTER TABLE user_permissions ADD CONSTRAINT FK_user_pe405324 
FOREIGN KEY (user_id) REFERENCES users (user_id);

INSERT INTO users(user_name) values('test_username');
INSERT INTO users(user_name) values('test_username2');

INSERT INTO permissions(permission_name) VALUES('permission_1')
INSERT INTO permissions(permission_name) VALUES('permission_2')

INSERT INTO user_permissions(user_id, permission_id, value)
VALUES(1, 1, 1)

INSERT INTO user_permissions(user_id, permission_id, value)
VALUES(2, 1, 1)

EDIT: Query so far

SELECT a.user_id, b.permission_id, 1 as 'value'
FROM USER_PERMISSIONS a right outer join 
PERMISSIONS b on a.permission_id = b.permission_id

Answer 1

insert into user_permissions (user_id, permission_id)
select
  u.user_id,
  p.permission_id
from
  users u
  cross join permissions p
where
  not exists (select 0 from user_permissions with (updlock, holdlock)
              where user_id = u.user_id and permission_id = p.permission_id)

Reference: Only inserting a row if it's not already there

Answer 2

INSERT dbo.user_permissions([user_id], permission_id, [value])
SELECT u.[user_id], p.permission_id, 1
FROM dbo.user_permissions AS u 
CROSS JOIN dbo.[permissions] AS p
WHERE NOT EXISTS (SELECT 1 FROM dbo.user_permissions 
  WHERE [user_id] = u.[user_id]
  AND permission_id = p.permission_id
)
GROUP BY [user_id], p.permission_id;

As an aside, you should avoid names that tend to require delimiters, e.g. user_id and permissions are keywords/reserved words.

Answer 3

Mansfield, If I understand you correctly, you want to seed the user_permissions table with a value when you add a new permission.

I'll also assume that you want it to default to 0. After inserting the new permission, running this code will seed the user_permissions table for all users with a default value of 0 for any permissions currently not in use.

--insert into permissions(permission_name) values('newperm');
--select * from permissions
insert into user_permissions(user_id, permission_id, value)
select
  u.user_id, p.permission_id, 0
from
             users u
  cross join permissions p
where
      p.permission_id not in(select permission_id from user_permissions)
;
--select * from user_permissions;

Answer 4

The below query will give you the missing userpermission rows to be inserted:

select a.USER_ID,b.permission_id from users a,permissions b,user_permissions c
   where c.user_id <>a.user_id and c.permission_id <> b.permission_id