-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: 18 February 2003 08:26
If I remove the '|| die' part from the mysql_query()
statement, it works
fine. This is bizarre, but there it is.
ie, if I have:
$result = mysql_query(SELECT * FROM SOME_TABLE);
it works.
If I have:
$result = mysql_query(SELECT * FROM SOME_TABLE) || die
(Unable to execute
SQL query);
it doesn't work. It gives me: Supplied argument is not a valid MySQL
result resource
The || and OR operators, although both doing a Boolean or, have different priorities,
so:
$result = mysql_query(...) or die(...);
is the same as
($result = mysql_query(...)) or die(...);
whilst
$result = mysql_query(...) || die(...);
is the same as
$result = (mysql_query(...) || die(...));
In the first case, the result of mysql_query() is assigned into $result, and if it
returns FALSE the die() is performed. In the second case, the result of applying the
|| operator to the mysql_query() and the die() is assigned to $result; because PHP
uses short-circuit evaluation, the die() is still only executed if mysql_query returns
FALSE, but the || operator still returns a simple Boolean to be assigned to $result --
which, if the die() hasn't fired, must be TRUE (which PHP generally prints as 1). QED.
Cheers!
Mike
-
Mike Ford, Electronic Information Services Adviser,
Learning Support Services, Learning Information Services,
JG125, James Graham Building, Leeds Metropolitan University,
Beckett Park, LEEDS, LS6 3QS, United Kingdom
Email: [EMAIL PROTECTED]
Tel: +44 113 283 2600 extn 4730 Fax: +44 113 283 3211
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