MySQL Bugs: #30526: Manual, Precedence of XOR

Bug #30526	Manual, Precedence of XOR
Submitted:	21 Aug 2007 2:21	Modified:	7 Sep 2007 2:09
Reporter:	Marc ALFF	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:		OS:	Any
Assigned to:	Paul DuBois	CPU Architecture:	Any

Description:
The following statement :

select TRUE OR TRUE XOR TRUE

does not return the same result between 4.1 and 5.0

In 4.1.24:
select TRUE OR TRUE XOR TRUE;
TRUE OR TRUE XOR TRUE
0

In 5.0.48:
select TRUE OR TRUE XOR TRUE;
TRUE OR TRUE XOR TRUE
1

The relative priority or the OR and XOR operators have changed in 5.0

How to repeat:
See description

Suggested fix:
Both 4.1 and 5.0 have been in production for too long,
it's too late to change the code behavior since this will introduce a non
compatible change in 5.0

Suggested fix:
Document this (so far undetected) regression in the manual,
and document the current priority of the XOR operator.

Thank you for the report.

Verified as described.

See the parser_precedence.test tests cases, for operator precedence.

In the 5.0 manual and above,
XOR should be in a line by itself, between OR and AND:
OR has a lesser precedence that XOR, which has a lesser precedence that AND

Also, note that listing "||" as the same precedence as "OR" is incorrect:
this might not be the case depending on SQL_MODE PIPE_AS_CONCAT

Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant products.

Updated the precedence of XOR.

Also noted the change in precedence for || if PIPES_AS_CONCAT
is enabled.