How Can I Effectively Use PDO's IN Clause with Arrays in PHP?

PHP - Using PDO with IN Clause Array

PDO excels in executing statements with IN clauses when using arrays for their values, as illustrated in the following code:

$in_array = [1, 2, 3];
$in_values = implode(',', $in_array);
$my_result = $wbdb->prepare("SELECT * FROM my_table WHERE my_value IN (?)");
$my_result->execute([$in_values]);
$my_results = $my_result->fetchAll();

However, the following code exhibits unexpected behavior:

$in_array = [1, 2, 3];
$in_values = implode(',', $in_array);
$my_result = $wbdb->prepare("SELECT * FROM my_table WHERE my_value IN (:in_values)");
$my_result->execute([':in_values' => $in_values]);
$my_results = $my_result->fetchAll();

Instead of returning all items whose my_value matches values in $in_array, this code only returns the item whose my_value matches the first item in $in_array.

PDO is not equipped to handle such scenarios effectively. To use arrays in IN clauses, we must dynamically generate a string with placeholders and insert it into the query. With positional placeholders, the solution is as follows:

$in = str_repeat('?,', count($in_array) - 1) . '?';
$sql = "SELECT * FROM my_table WHERE my_value IN ($in)";
$stm = $db->prepare($sql);
$stm->execute($in_array);
$data = $stm->fetchAll();

For cases with multiple placeholders, consider leveraging array_merge(). For instance:

$arr = [1, 2, 3];
$in = str_repeat('?,', count($arr) - 1) . '?';
$sql = "SELECT * FROM table WHERE foo=? AND column IN ($in) AND bar=? AND baz=?";
$stm = $db->prepare($sql);
$params = array_merge([$foo], $arr, [$bar, $baz]);
$stm->execute($params);
$data = $stm->fetchAll();

In scenarios with named placeholders, the process is more intricate, as it involves generating a sequence of placeholders, for example, :id0, :id1, :id2.

$ids = [1, 2, 3];
$in = "";
$i = 0;
foreach ($ids as $item) {
    $key = ":id" . $i++;
    $in .= ($in ? "," : "") . $key;
    $in_params[$key] = $item;
}

$sql = "SELECT * FROM table WHERE id IN ($in)";
$stm = $db->prepare($sql);
$stm->execute(array_merge($params, $in_params));
$data = $stm->fetchAll();

Fortunately, named placeholders do not necessitate strict order, allowing for merging of arrays in any sequence.

The above is the detailed content of How Can I Effectively Use PDO's IN Clause with Arrays in PHP?. For more information, please follow other related articles on the PHP Chinese website!