php中的array_key_exists与NULL值没有输出

Question

I have the following query:

//product density
$stmt_density = $conn->prepare("SELECT density FROM product_density
WHERE product_id = :productid ");
$stmt_density->execute(array(':productid' => "$pid"));
$density = $stmt_density->fetchAll(); 

If density is not present the value will be "NULL".

var_dump($density);

gives following output:

array(1) { [0]=> array(2) { ["density"]=> NULL [0]=> NULL } } 

I need to check whether the array is having values or not and to provide select options, if array not empty.

Answer 1

Depending on whether you expect to get back multiple results from your query could change the answer, especially if you get back say 1 result with a NULL and one without. But you could do...

function validResult($density) {
    foreach($density as $item) {
        if($item["density"] == NULL) return false;
    }
    return true;
 }


 if(validResult($density))
     echo "We have values";
 else
     echo "Array contains null";

The function will return false if any result has null, regardless of how many are not null