Flag system in SQL

MySQL can handle hexa digits well (0x0020 == 32 == b0100000)
Hexa digits are easier to read and write, than binary numbers. Actually it processes the binary logical operations.
flag_a = 0x0001
flag_b = 0x0002
flag_c = 0x0004
flag_d = 0x0008
flag_e = 0x0010
flag_f = 0x0020
...


Theorem:
^^^^^^^

bit union: |
  0100  (4)
  0010  (2)
-----------
| 0110  (6)

bit section: &
  0110  (6)
  0010  (2)
-----------
& 0010  (2)

bit abstraction: & ~
  0110  (6)
  0010  (2)
  .........
  0110  (6)
  1101  (~2)
-----------
&~0100  (4)



Examples with numbers:
^^^^^^^^^^^^^^^^^^^^^

CHECK:
SELECT 33 & 0x0020;   # is flag set? -> yes 32
SELECT 12 & 0x0020;   # is flag set? -> no  0

SET:
SELECT (33 | 0x0020);             # -> 33
SELECT (10 | 0x0020);             # -> 42

DELETE:
SELECT (33 & ~ 0x0020);           # ->  1

TOGGLE:
SELECT (33 ^ 0x0020);             # ->  1
SELECT ((33 ^ 0x0020) ^ 0x0020);  # -> 33



Database examples:
^^^^^^^^^^^^^^^^^

[ CHECK ]
Is flag set?
SELECT * FROM table WHERE flags & 0x0020 = 0x0020 ;    # this is nice and readable
SELECT * FROM table WHERE (flags & 0x0020);            # this is easy

Is flag unset?
SELECT * FROM table WHERE flags & 0x0020 = 0;          # this is nice and readable
SELECT * FROM table WHERE !(flags & 0x0020);           # this is easy

[ SET ]
UPDATE table SET flags = flags | 0x0020;

[ DELETE ]
UPDATE table SET flags = flags & ~0x0020;

[ TOGGLE ]
UPDATE table SET flags = flags ^ 0x0020;



[ Multiple flag CHECKing ]
Let user privileges
PRIV_ADMIN   = 0x0001;
PRIV_LEARNER = 0x0008;

Get users which have ADMIN or LEARNER privileges!
SELECT * FROM users WHERE priv & (0x0008 | 0x0001) = (0x0008 | 0x0001);

Get users which have both ADMIN and LEARNER privileges!
SELECT * FROM users WHERE priv & (0x0008 | 0x0001) > 0;      # this is nice and readable
SELECT * FROM users WHERE (priv & (0x0008 | 0x0001));        # this is easy

Get users which have nor ADMIN, nor LEARNER privileges!
SELECT * FROM users WHERE priv & (0x0008 | 0x0001) = 0;      # this is nice and readable
SELECT * FROM users WHERE !(priv & (0x0008 | 0x0001));       # this is easy

[ Multiple flag SETting ]
Let user be an ADMIN and a LEARNER too!
UPDATE users SET priv = priv | (0x0008 | 0x0001);

[ Multiple flag DELETEing ]
Delete ADMIN and LEARNER privilege of the user!
UPDATE users SET priv = priv & ~(0x0008 | 0x0001);

[ SET and DELETE flags at the same time ]
Give the user ADMIN privilege but take LEARNER privilege away!
UPDATE users SET priv = priv | (0x0001) & ~ (0x0008);

In this case we can use multiple flags to SET and UNSET using the | operation.
UPDATE users SET priv = priv | (0x0001 | 0x0020) & ~ (0x0008 | 0x0040);