 | | | Subject: NULL values returning as empty string | Subject: NULL values returning as empty string 2007-10-23 - By Larry Low
Back
I am unable to figure out why but NULL values which from what I read should
be undefined are being defined. See the example below for the column
thold_hi which shows as NULL in the database but the reference
$row->{'thold_hi'} being defined.
I am running mysql 5.0.22 and DBI 1.58.
Example:
my $sql = "SELECT t.lastread,t.thold_hi,t.thold_low,thold_alert,bl_alert
FROM host h LEFT JOIN data_local dl ON h.id=dl.host_id LEFT JOIN
data_template_rrd dr ON dr.local_data_id=dl.id LEFT JOIN thold_data t ON
t.data_id=dr.id WHERE h.description='something' AND
dr.data_source_name='hdd_free'";
my $sth = $dbh->prepare($sql);
$sth->execute();
my $row = $sth->fetchrow_hasref();
if (!defined($row->{'thold_hi'})) {
print "Not Defined\n";
} else {
print "Defined\n";
}
mysql> SELECT t.lastread,t.thold_hi,t.thold_low,thold_alert,bl_alert FROM
host
h LEFT JOIN data_local dl ON h.id=dl.host_id LEFT JOIN data_template_rrd dr
ON
dr.local_data_id=dl.id LEFT JOIN thold_data t ON t.data_id=dr.id WHERE
h.description='something' AND dr.data_source_name='hdd_free';
+-- ---- --+-- ---- --+-- ---- ---+-- ---- -----+-- ---- --+
| lastread | thold_hi | thold_low | thold_alert | bl_alert |
+-- ---- --+-- ---- --+-- ---- ---+-- ---- -----+-- ---- --+
| 24997856 | NULL | 25000000 | 1 | 0 |
+-- ---- --+-- ---- --+-- ---- ---+-- ---- -----+-- ---- --+
1 row in set (0.00 sec)
----
Larry Low
4150 N Drinkwater Blvd., 5th Floor
Scottsdale, AZ 85251
E-mail: llow@(protected)'
Telesphere Networks, Inc
--
MySQL Perl Mailing List
For list archives: http://lists.mysql.com/perl
To unsubscribe: http://lists.mysql.com/perl?unsub=mysql@(protected)
|
|
|