Question

Situation

I want to convert certain status fields within my PHP/MySQL application to handle more than one at any time. Take below what is currently an ENUM field as an example:

STATUS_ACTIVE
STATUS_FROZEN
STATUS_PENDING
STATUS_FLAGGED
STATUS_DELETED

Currently, it will only support one at a time. However by converting the set in to binary, I end up up with a set of strings.

1     STATUS_ACTIVE
10    STATUS_FROZEN
100   STATUS_PENDING
1000  STATUS_FLAGGED
10000 STATUS_DELETED

Now, when it comes to filtering PHP wise, I have no issues. However, this introduces a large (and unnecessary) overhead. It is very possible an entry could end up as

10010
01110
etc.

Question

I’ve done some digging around and the best piece of information I have found was actually on stackoverflow (ironically) here. Can someone please explain the actual syntax used there or point me to a correct MySQL manual page.

It’s not very clear just how one would hypothetically go about these situations:

Changing only the third bit
Searching for 1 on only the fourth bit
Updating two binary flags at the same time

It would be really appreciated to have even a knock in the right direction, thanks for reading.

Edit: I have figured out most of the syntax. My question now: is it possible to change more than one bit at a time without having to redefine the whole thing?

I.e

100 -> 1011
1 -> 101

Answer 1

Answering your updated question. For example we need 3 and 5 bits.

If you need to SET 3 and 5 bits you should OR your field with 10100

UPDATE table SET options = options | ((1 << 2) | (1 << 4))

If you need to CLEAR 3 and 5 bits you should AND your field with 11101011 = NOT(10100)

UPDATE table SET options = options & (~((1 << 2) | (1 << 4)))