MySQL Bugs: #65727: Unicode minus sign should be accepted as minus-operator

Bug #65727	Unicode minus sign should be accepted as minus-operator
Submitted:	25 Jun 2012 12:24	Modified:	28 Jun 2012 19:38
Reporter:	Peter Laursen (Basic Quality Contributor)	Email Updates:
Status:	Won't fix	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:		OS:	Any
Assigned to:	Paul DuBois	CPU Architecture:	Any
Tags:	qc

Description:
(not sure about the category here!) 

references: 
http://www.fileformat.info/info/unicode/char/2212/index.htm
http://en.wikipedia.org/wiki/Plus_and_minus_signs

The latter says (but this is of course not law!): "The hyphen-minus sign (-) is the ASCII version of the minus sign, and doubles as a hyphen. It is usually shorter in length than the plus sign and sometimes at a different height. It can be used as a substitute for the true minus sign when the character set is limited to ASCII."

(also inspired by http://datacharmer.blogspot.dk/2012/06/hidden-mistake.html).

How to repeat:
SET NAMES utf8;
SELECT (7 − 2);  -- 'unicode minus' ; returns 1064 syntax error
SELECT (7 - 2);  -- 'hyphen-minus'  ; returns "5"

Suggested fix:
As all charsets involved here are Unicode, I think the Unicode minus sign should be a valid minus operator? If not, I think docs should clearly state that it is not so.

(but don't change the behavior of hyphen, please!)

OK - understood that the Unicode minus is primarily intended for typsesetting etc. Programming languages will (still mostly) use ASCII. So this is probably just a consequence of MySQL being a C-derivate.

So changing category to docs where 
http://dev.mysql.com/doc/refman/5.5/en/arithmetic-functions.html#operator_minus
and 
http://dev.mysql.com/doc/refman/5.5/en/arithmetic-functions.html#operator_unary-minus
.. could have a clarification. As I understand Shlomi's comment in Guiseppes blog it seems that CSV files with negative numbers will sometimes (when generated recent Excel versions?) use Unicode minus and LOAD DATA would then fail.

PostgreSQL and GCC don't accept Unicode minus, either. MySQL is not unusual in this regard.

PostgreSQL and GCC don't accept Unicode minus, either. MySQL is not unusual in this regard.