Bug #100223 unexpected returned result of & operation

• Submitted: 15 Jul 2020 7:12
• Modified: 15 Jul 2020 13:12
• Reporter: ick R
• Status: Not a Bug
• Category: MySQL Server
• Severity: S3 (Non-critical)
• Version: 8.0.21
• OS: Any
• CPU Architecture: Any

[15 Jul 2020 7:12] ick R

Description:
I'm not sure about the correctness of the results returned by 'select bin(-24656)  & bin(1);' (which is 1) and 'select bin(24656)  & bin(1);' (which is 0).How does '&' work in this process?

How to repeat:
select bin(-2456);
select bin(-24656)  & bin(1);

select bin(2456);
select bin(24656)  & bin(1);

[15 Jul 2020 7:38] ick R

Another case:
select CONV(-2456,10,2) & 1;
--1
select CONV(2456,10,2) & 1;
--0

[15 Jul 2020 8:11] ick R

sorry,it should be :
select bin(-24656);
select bin(-24656)  & bin(1);

select bin(24656);
select bin(24656)  & bin(1);

in HOW TO REPEAT

[15 Jul 2020 13:12] MySQL Verification Team

Hi Mr. R,

Thank you for your bug report.

However, this is not a bug, but a support question.

In short, the operator '&' works as a binary one and not as a logical one.

Also, please read the following comment.

[15 Jul 2020 13:12] MySQL Verification Team

We're sorry, but the bug system is not the appropriate forum for asking help on using MySQL products. Your problem is not the result of a bug.

For details on getting support for MySQL products see http://www.mysql.com/support/
You can also check our forums (free) at http://forums.mysql.com/

Thank you for your interest in MySQL.

[15 Jul 2020 13:25] Yushan ZHANG

I think the bug is related to the `&` result:

select CONV(-2456,10,2);
-- incorrect 5.7.31 & 8.0.21
select CONV(-2456,10,2) & 1;
select (-2456) & 1;

It is a bitwise operation, then the second query should give the same result as the last one, however, it returns 1.

[15 Jul 2020 13:27] Yushan ZHANG

Forgot to append the result to the queries:

-- incorrect
mysql> select CONV(-2456,10,2) & 1;
+----------------------+
| CONV(-2456,10,2) & 1 |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)

mysql> select (-2456) & 1;
+-------------+
| (-2456) & 1 |
+-------------+
|           0 |
+-------------+
1 row in set (0.00 sec)