Question

I’m getting the following errors when trying to loop through an array on my server to bind statements with PDO:

“Only variables can be passed by reference”
or
“Cannot pass parameter 2 by reference pdo”

Works fine on my local XAMPP.

Code:

$sql = rest of sql query etc.

$loop = 1;
foreach ($animal_array $ani)
{
    if ($loop == 1) {$sql .= " WHERE animal.id= :animal_id".$loop; }
    else            {$sql .= " OR animal.id= :animal_id".$loop;}
    $loop++;
}   

$stmt = $crud->db->prepare($sql);

$loop = 1;
foreach ($animal_array as $ani)
{   
    $stmt->bindParam(':animal_id'.$loop, $ani['animal_id'], PDO::PARAM_STR);
    $loop++;
}

Also tried this at the end as I read somewhere that concatonations sometimes aren’t liked:

foreach ($animal_array as $ani)
{   
    $ref = ":animal_id".$loop;
    $stmt->bindParam($ref, $ani['animal_id'], PDO::PARAM_STR);
    $loop++;
}

.

EDIT:
The array contains other values, sort of like this:

$animal_array['animal_id'];
$animal_array['name'];
$animal_array['colour'];
$animal_array['quantity']; etc

Answer 1

You ought to use bindValue for pure input parameters. The bindParam method is reserved for binding variables which can be used as input but also return query results (output).

Though that doesn’t explain your issue. But we don’t know what your array contains.
It’s not the key generation / concatenation for sure.