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

Answer 1

$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.