Complex select in SQLite view - sqlite

Question

I have two tables where Security holds the access bit mask for a given NTFS file system scan and FileSystemRights which equates to the string representations for the well known bit masks. I need to create a view which exposes the expected (not just proper) string representations for a given bit mask. The problem is several enum values composite and contain combinations of lower values, so the desired idea is not to repeat the implicit values.
For example, a value of 1179817 (Security.Id = 24) should only report ReadAndExecute and Synchronize, excluding ExecuteFile, ListDirectory, Read, ReadAttributes, ReadData, ReadExtendedAttributes, ReadPermissions and Traverse, as those are all part of ReadAndExecute (eg. ReadAndExecute & Read == Read). Its obviously correct to show them all, but a user wants only to see the non implicit values.
I'm lost within the constraints of SQL to produce a join that behaves like this without some abysmal nested case that would be a nightmare to look at.
Does a better programmatic approach exist?
FileSystemRights
================
Id Name Value
-- ---- -----
1 None 0
2 ListDirectory 1
3 ReadData 1
4 WriteData 2
5 CreateFiles 2
6 CreateDirectories 4
7 AppendData 4
8 ReadExtendedAttributes 8
9 WriteExtendedAttributes 16
10 ExecuteFile 32
11 Traverse 32
12 DeleteSubdirectoriesAndFiles 64
13 ReadAttributes 128
14 WriteAttributes 256
15 Write 278
16 Delete 65536
17 ReadPermissions 131072
18 Read 131209
19 ReadAndExecute 131241
20 Modify 197055
21 ChangePermissions 262144
22 TakeOwnership 524288
23 Synchronize 1048576
24 FullControl 2032127
25 GenericAll 268435456
26 GenericExecute 536870912
27 GenericWrite 1073741824
28 GenericRead 2147483648
Security
========
Id FileSystemRights IdentityReference
-- ---------------- -----------------
20 2032127 BUILTIN\Administrators
21 2032127 BUILTIN\Administrators
22 2032127 NT AUTHORITY\SYSTEM
23 268435456 CREATOR OWNER
24 1179817 BUILTIN\Users
25 4 BUILTIN\Users
26 2 BUILTIN\Users
MyView
======
SELECT s.Id AS SecurityId,
f.Name
FROM Security s
JOIN FileSystemRights f
ON CASE f.Value
WHEN 0 THEN s.FileSystemRights = f.Value
ELSE (s.FileSystemRights & f.Value) == f.Value
END
ORDER BY s.Id, f.Name;

Answer 1

Add the actual value of the name to the query.
Then wrap another query around that to filter out values for the same entry that are a subset of another value:
WITH AllValues(SecurityId, Name, Value) AS (
SELECT s.Id,
f.Name,
f.Value
FROM Security s
JOIN FileSystemRights f
ON CASE f.Value
WHEN 0 THEN s.FileSystemRights = f.Value
ELSE (s.FileSystemRights & f.Value) == f.Value
END
)
SELECT SecurityId,
Name
FROM AllValues
WHERE NOT EXISTS (SELECT *
FROM AllValues AS AV2
WHERE AV2.SecurityId = AllValues.SecurityId
AND (AV2.Value & AllValues.Value) != 0
AND AV2.Value > AllValues.Value
)
ORDER BY 1, 2;