empty query

[Anon]

how can i know if the feild is empty?
this isnt working.
anyone?
<?
mysql_connect("","","");
mysql_select_db("message");
$query=mysql_query("select * from online")or die(mysql_error());
while($row=mysql_fetch_array($query))
{
if(empty($row['un_online_2_send']))
{
print "empty";
}
else
echo $row['un_online_2_send;
?>

[matto]

in php (e.g.):
if($variable)
or:
if($variable != '')

and in sql:
select ... from ... where field is null
(/is not null)

[[deleted]]

A few notes:

NULL != ''

If your database contains an empty string, you cannot find that by looking for NULL:

SELECT FROM table WHERE field=NULL;
is different from
SELECT FROM table WHERE field="";

and

if ($variable) does NOT check to see if there is a value in $variable, it only checks wether it contains something other than zero. If $variable is not defined, this line will give an error.

look at this:

error_reporting(E_ALL);

if (isset($var))
{
echo 'var set<BR>';
}
else
{
echo 'var not set<BR>';
}

if (empty($var))
{
echo 'var is empty<BR>';
}
else
{
echo 'var is not empty<BR>';
}

if ($var)
{
echo 'var "is"<BR>';
}
else
{
echo 'var "is" not<BR>';
}

try it out without defining $var, then with
$var=0;
and then with
$var=1;

you'll see different answers every time.