MySQL Bugs: #34090: Wrong result when computing unsigned

Bug #34090	Wrong result when computing unsigned
Submitted:	27 Jan 2008 13:35	Modified:	28 Jan 2008 5:28
Reporter:	Florent Palomares	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server: Data Types	Severity:	S3 (Non-critical)
Version:	MySQL - 5.0.22	OS:	Microsoft Windows (XP)
Assigned to:		CPU Architecture:	Any

Description:
Hi,

I have a weird  behavior when computing unsigned int,
the result seems to be considered as unsigned too...
so, if the expected value was negative, the given value
is a positive number!

Regards,
Florent

How to repeat:
CREATE TABLE test (
  `a` tinyint(3) unsigned NOT NULL,
  `b` tinyint(3) unsigned NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO test VALUES (1, 2);

SELECT * , 2 * a -2 * b FROM test

=> I have :
 a  	 b  	 2 * a - 2 * b
1 	2 	18446744073709551614

Sorry, but formally this is not a bug. Read http://dev.mysql.com/doc/refman/5.0/en/arithmetic-functions.html:

"If one of the arguments is an unsigned integer, and the other argument is also an integer, the result is an unsigned integer."