无法从SQL结果php获取实际值

Question

I am having some trouble getting some values from my sql query in php

This is my php code:

<?php
    include "init.php";

    $stmt = "SELECT email FROM Customer ";
    $result = $dbcon -> prepare($stmt);
    $result->execute();
    $result->store_result();
    while($result -> fetch()){
        // This line below works
        echo "Works";

        // This doesn't work
        echo $result['email'];
    }

?>

Answer 1

You need to use bind_result() to retrieve the values returned by the query.

include "init.php";

$stmt = "SELECT email FROM Customer ";
$result = $dbcon -> prepare($stmt);
$result->execute();
$result->store_result();
$result->bind_result($email);
while($result -> fetch()){
    // This line below works
    echo "Works";

    echo $email;
}

Answer 2

To start, mysqli::prepare doesn't return a mysqli_result , it returns a mysqli_stmt . You then have to execute that mysqli_stmt and either fetch directly from it into a bound variable, or extract a mysqli_result and fetch from that. There are several ways to do what you want:

$qry = "SELECT email FROM Customer ";
$stmt = $dbcon->prepare($qry);
$stmt->execute();
$stmt->bind_result($email);  // Bind variable to statement
while($stmt->fetch())        // Iterate through statement
{
    // This line below works
    echo "Works";

    echo $email;
}

Or:

$qry = "SELECT email FROM Customer ";
$stmt = $dbcon->prepare($qry);
$stmt->execute();
$rslt = $stmt->get_result();       // Retrieve result set
while($row = $rslt->fetch_assoc()) // Iterate through result
{
    // This line below works
    echo "Works";

    echo $row['email'];
}

Or:

$qry = "SELECT email FROM Customer ";
$stmt = $dbcon->prepare($qry);
$stmt->execute();
$rslt = $stmt->get_result();                 // Retrieve result
$resArray = $rslt->fetch_all(MYSQLI_ASSOC)); // Convert to array
foreach ($resArray as $row)                  // Iterate through array
{
    // This line below works
    echo "Works";

    echo $row['email'];
}

As is my custom, I leave error handling as an exercise for the reader.