Mysql NULL field and php isset?

Question

I have data in my mysql fields which are NULL

But in php when getting the data into an array how come I can compare the value of it without first using php's isset?

Example,

$var = null;

if ($var == 123123) // GENERATES ERROR AS DIDN'T CHECK IF IT WAS SET FIRST

But in mysql

$q = $dbc -> prepare("SELECT nullColumn FROM table_1");
$q -> execute();
$null = $q -> fetch(PDO::FETCH_ASSOC);
if ($null['nullColumn'] == 2312312) // DOESN'T GENERATE ERROR EVEN THOUGH VALUE IS NULL

I have also used var_dump on the value and it returns NULL

why don't you want to use isset? please provide a code example so that we can understand your use case — Alp
– Alp, Commented Mar 4, 2012 at 23:48
You don't have to use isset if your value is null. You might be mixing something up here. Care for an illustrative code sample? — deceze
– deceze ♦, Commented Mar 4, 2012 at 23:50

deceze · Accepted Answer · 2012-03-04 23:57:01Z

3

$var = null;

if ($var == 123123) // GENERATES ERROR AS DIDN'T CHECK IF IT WAS SET FIRST

This premise is false! The above code will not generate an error, because the variable $var exists.

Trying to use a variable which does not exist, i.e. which hasn't been declared anywhere, generates an error. Trying to use a declared variable whose value is null is perfectly legit.

See The Definitive Guide To PHP's isset And empty for an in-depth look into this topic.

answered Mar 4, 2012 at 23:57

deceze♦

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Comments

dotoree · Accepted Answer · 2012-03-04 23:51:49Z

0

I guess depends on the driver. PDO fetches NULL for NULL fields. Don't have to use isset, use is_null($field) or null === $field

answered Mar 4, 2012 at 23:51

dotoree

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