PHP array_column(): Get One Column from Rows

array_column($rows, $column) returns the value of $column from every row in a list of rows. It turns a table of records into a flat array of one field, which is what you need before implode, in_array, array_sum or array_search.

<?php
$users = [
    ["id" => 3, "name" => "Ada", "email" => "ada@example.com"],
    ["id" => 7, "name" => "Bob", "email" => "bob@example.com"],
    ["id" => 9, "name" => "Cy", "email" => "cy@example.com"],
];

$emails = array_column($users, "email");
print_r($emails);

echo implode(", ", array_column($users, "name")), "\n";

The rows can come from anywhere: a decoded JSON response, a CSV file, or a database query that returned an array of associative arrays.

Use the index key to build key value pairs

The third argument names a field whose value becomes the key of each result. array_column($users, 'name', 'id') is the usual way to build an id to name lookup, for example for a <select> list.

<?php
$users = [
    ["id" => 3, "name" => "Ada", "role" => "admin"],
    ["id" => 7, "name" => "Bob", "role" => "editor"],
    ["id" => 9, "name" => "Cy", "role" => "viewer"],
];

$names = array_column($users, "name", "id");
print_r($names);

echo $names[7], "\n";

If two rows share the same index value, the later row overwrites the earlier one.

Index whole rows by id with null

Pass null as the column to keep each full row, re-keyed by the index field. Looking a row up by id is then a direct key access instead of a loop.

<?php
$products = [
    ["sku" => "A12", "name" => "Lamp", "price" => 29],
    ["sku" => "B07", "name" => "Desk", "price" => 199],
    ["sku" => "C33", "name" => "Chair", "price" => 89],
];

$bySku = array_column($products, null, "sku");

$sku = "B07";
if (isset($bySku[$sku])) {
    echo "{$bySku[$sku]['name']} costs {$bySku[$sku]['price']}\n";
}

print_r(array_keys($bySku));

Build the index once and every lookup after that is instant, which matters when you look up many ids in a loop.

Find a row with array_column and array_search

To find which row has a given value, search the column and use the position you get back. Check the result with !== false, because a match in the first row returns 0.

<?php
$users = [
    ["name" => "Ada", "email" => "ada@example.com"],
    ["name" => "Bob", "email" => "bob@example.com"],
    ["name" => "Cy", "email" => "cy@example.com"],
];

$wanted = "bob@example.com";
$index = array_search($wanted, array_column($users, "email"));

if ($index !== false) {
    echo "Found: {$users[$index]['name']} at position $index\n";
} else {
    echo "No user with $wanted\n";
}

// Just checking existence
var_dump(in_array("zoe@example.com", array_column($users, "email"), true));

This relies on $users having the keys 0, 1, 2, because array_column returns a list. If the array was filtered and has gaps, call array_values($users) first. The array_search page covers the false versus 0 pitfall in detail.

Sum, count or average a column

array_column pairs well with the math helpers: extract the field, then add it up.

<?php
$cart = [
    ["item" => "Book", "qty" => 2, "price" => 12.5],
    ["item" => "Pen", "qty" => 10, "price" => 1.2],
    ["item" => "Bag", "qty" => 1, "price" => 30.0],
];

$qtys = array_column($cart, "qty");
echo "Items: " . array_sum($qtys) . "\n";

$prices = array_column($cart, "price");
echo "Most expensive: " . max($prices) . "\n";
echo "Average price: " . round(array_sum($prices) / count($prices), 2) . "\n";

$total = array_sum(array_map(fn($row) => $row["qty"] * $row["price"], $cart));
echo "Total: $total\n";

For a value computed from several fields, like quantity times price, array_map is the tool, as in the last line.

array_column with objects

With a list of objects, array_column reads public properties. Private and protected properties are not visible to it.

<?php
class User
{
    public function __construct(
        public int $id,
        public string $name,
        private string $password,
    ) {}
}

$users = [
    new User(1, "Ada", "x"),
    new User(2, "Bob", "y"),
];

print_r(array_column($users, "name", "id"));
var_dump(array_column($users, "password"));

The second call returns an empty array: password is private, so every object is skipped.

Rows with a missing field are skipped

array_column does not fill in a placeholder for a row that lacks the field. The result can be shorter than the input, so its positions no longer match the rows.

<?php
$people = [
    ["name" => "Ada", "phone" => "555-0101"],
    ["name" => "Bob"],
    ["name" => "Cy", "phone" => "555-0199"],
];

print_r(array_column($people, "phone"));

// Keep the link to each person with an index key
print_r(array_column($people, "phone", "name"));

The first result has two phones and no hint that Bob had none. With the name as the index key, you can see whose number is whose, which is the safer form whenever some rows may lack the field.