MySQL Bugs: #36719: FOUND_ROWS() reports previous after an error

Bug #36719	FOUND_ROWS() reports previous after an error
Submitted:	14 May 2008 18:03	Modified:	23 May 2008 15:30
Reporter:	John Larsen	Email Updates:
Status:	Closed
Category:	Server: Docs	Severity:	S3 (Non-critical)
Version:	4.1,5.0,5.1,6.0 BK	OS:	Any
Assigned to:	Paul DuBois	Target Version:
Triage:	D4 (Minor)

Description:
Using PHP mysql_connect()

mysql_query("SELECT 1");  //for instance then
mysql_query("SELECT SQL_CALC_FOUND_ROWS blah FROM blah");  //where this query returns an
error instead of a result
mysql_query("select FOUND_ROWS() as c");   //This returns the result of the previous
query before the error in this case a 1

I don't know if I would call that a bug, but preferably I think a result of 0 would be
preferable?

How to repeat:

mysql_query("SELECT 1");  //for instance then
mysql_query("SELECT SQL_CALC_FOUND_ROWS blah FROM blah");  //where this query returns an
error instead of a result
mysql_query("select FOUND_ROWS() as c");   //This returns the result of the previous
query before the error in this case a 1

Thank you for the report.

Verified as described. Probably can be considered as documentation request.

Paul, this is not a bug in the server.
The value of FOUND_ROWS() is reset by the next successful SELECT statement.
I've read the manual article,
http://dev.mysql.com/doc/refman/4.1/en/information-functions.html
and it's sufficient. 
Perhaps it would be enough to add to the manual that beyond the given description the
behaviour of FOUND_ROWS() is unspecified.

Changing to Documentation category.

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 documentation per comment from Konstantin: FOUND_ROWS() behavior undefined except
as described. Also pointed out that it is set for *successful* SELECT statements (to avoid
implying that failed statements set it).