将第一个结果值存储到PHP中的sql查询变量中

Question

I am trying to store the result from an sql query into a variable in my php query. But thing is, it is not working, simply because I am making schoolboy errors and due to my lack of experience in php.

This is my code:

<?php
    include "init.php"
    if(!empty($_POST['driverNo'])){
        $driverNoText = $_POST['driverNo'];
        $stmt = "SELECT registrationNo FROM cars WHERE driverNo = ?";
        $result = $conn->prepare($stmt);
        $result->bind_param('s', $driverNoText);
        $result->execute();
        $result->store_result();

        if($result->num_rows > 0){
            $registrationNo = $result["registrationNo"];
            echo $registrationNo;
        }
        else{
            $registrationNo = "";
        }
    }
    else{
        echo "Something went horribly wrong";
    }
?>  

Please note that as both the registrationNo and driverNo are both unique then the result will either return 0 records (not found) OR just 1 (found).

I just want to store the registrationNo into the $registrationNo, because I need to use that value elsewhere later.

Would mean a lot if someone could help me fix my error

Thanks

Answer 1

You have to use ->bind_result() for that:

$result = $conn->prepare( $stmt );
$result->bind_param( 's', $driverNoText );
$result->execute();
$result->store_result();

$result->bind_result( $registrationNo );

while( $result->fetch() )
{
    echo $registrationNo;
}

$result->free_result();

Note that the use of ->store_result() in your example is not necessary (although it is not an error): it doesn't “store the first result”, it store all result set in php side. Your script will work even without using it.

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• Read more about bind_result
• Read more about store_result