PHP数组比较和过滤

Question

I'm newer to PHP and sorting out some code. This is taking two phone number lists… then pulling the numbers in the 2nd list OUT of the first list, making a new filtered list. The full code worked fine when just pulling in one list. Now that I've modified it to filter the list based a 2nd list, the code now fails and I'm getting this warning:

Warning: Illegal string offset 'phone_number' in /var/www/html/send.php on line 7

    // Get all of the phone numbers from the List
$sql = "SELECT phone_number FROM dial_list WHERE list_id='$list'";
$result = mysqli_query($link, $sql);
echo mysqli_error($link);
foreach ($result as $row) 
    {
      $all_people[] = $row['phone_number'];
    }

// Get phone numbers from our DNC list
$sql = "SELECT phone_number FROM dial_dnc";
$result = mysqli_query($link, $sql);
echo mysqli_error($link);

    foreach ($result as $row) 
    {
      $dnc_people[] = $row['phone_number'];
    }

// Remove DNC numbers from list
$filtered_people = array_diff($all_people, $dnc_people);
    foreach ($filtered_people as $row)
    {
      $people[] = $row['phone_number'];
    }

Line 79 (where the warning comes from) is: $people[] = $row['phone_number'];

Any help to pinpoint the error or an improvement on how to accomplish this filtering would be greatly appreciated!

Answer 1

You forgot to fetch results from your resultset

foreach ($result as $row) {

should be

while ($row = mysqli_fetch_assoc($result)) {

Answer 2

This can be easily done with mysql alone.

SELECT 
dl.phone_number 
FROM dial_list AS dl 
INNER JOIN dial_dnc as dnc 
ON (dl.phone_number = dnc.phone_number)
WHERE list_id='$list'

Answer 3

your $result is a traversable object, not an array. as seen in the docs

Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.

You can loop over the results in 2 different ways:

// precedural style
while ($row = mysqli_fetch_assoc($result)) { ... }
// OOP style
while($row = $result->fetch_assoc()) { ... }

Answer 4

Since you assign $all_people and $dnc_people with $row['phone_number'] , $filtered_people doesn't have a phone_number key, instead being number-keyed, probably. Try

foreach($filtered_people as $key => $value)
{
    $people[] = $value;
}