How can i create view using the SYSTEM_USER's permission path in query - sql

Question

I am attempting to make a view of a table that uses the current user's user name (System_user) with their log in information ([permission path]) which tells me which subset of the data they are allowed to see in the view. Views cannot be created with variables or temporary tables so made an attempt at user defined functions to return a table but it appears to be a bit beyond my current skills.
It works as a Query
DECLARE #user as varchar(50)
SELECT #user = SYSTEM_USER
CREATE TABLE LoginInformation(
[account name] varchar(50),
[type] varchar(50),
[privilege] varchar(50),
[mapped login name] varchar(50),
[permission path] varchar(50)
)
INSERT LoginInformation
EXEC xp_LoginInfo #AcctName = #user, #Option = 'all';
SELECT * FROM SomeTableName
WHERE Permission IN (SELECT [permission path] FROM LoginInformation)
When creating a view I get stuck because I cannot declare a variable:
DECLARE #user as varchar(50)
SELECT #user = SYSTEM_USER
When I tried user defined functions i got held up because I could not Insert an Executed statement
INSERT LoginInformation
EXEC xp_LoginInfo #AcctName = #user, #Option = 'all';
I also do not appear to be able to do the simplest solution:
INSERT LoginInformation
EXEC xp_LoginInfo #AcctName = SYSTEM_USER, #Option = 'all';
Ideally i would have a function that took System_user as a parameter and gave me a table of just that user's [permission path]. I could then use that in my view's creation.
WHERE Permission IN (MyFunctionName(SYSTEM_USER))

Answer 1

xp_LoginInfo is a stored procedure. You can see its underlying code by running the following T-SQL statement:
sp_helptext xp_LoginInfo
Which produces the output:
create procedure sys.xp_logininfo
#acctname sysname = null, -- IN: NT login name
#option varchar(10) = null, -- IN: 'all' | 'members' | null
#privilege varchar(10) = 'Not wanted' OUTPUT -- OUT: 'admin' | 'user' | null
as
set nocount on
etc ...
My suggestion is to take the underlying SQL, tweak it if needed and use it in your view.

Answer 2

While doing additional research I found a much easier and different way of accomplishing my goal. I went with the Is_Member function. It accesses the permission path without having to work with SYSTEM_USER. I have done a few tests and it appears to do what I want.
CREATE VIEW [dbo].[vw_SomeTableName]
SELECT * FROM SomeTableName
where WHERE Is_Member( UserName ) = 1 )
The Is_Member function indicates whether the current user is a member of the specified Microsoft Windows group or SQL Server database role.
IS_MEMBER ( { 'group' | 'role' } )
Return value:
Current user is not a member of group or role, returns 0.
Current user is a member of group or role, returns 1.
Either group or role is not valid. When queried by a SQL Server login or a login using an application role, returns NULL for a Windows group.
For more on Is_Member check out msdn.microsoft.com on Is_Member or look at some other stack overflow questions.