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Why Doesn't PDO's IN Clause Work with Array Parameters, and How Can I Fix It?
Why Doesn't PDO's IN Clause Work with Array Parameters, and How Can I Fix It?
Dec 26, 2024 pm 02:17 PM
Using PDO with IN Clause Array
When using PDO to execute a statement with an IN clause that uses an array for its values, you may encounter unexpected behavior. This article explains why a specific approach doesn't work and provides alternative solutions.
Example:
$in_array = 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();
$my_results = $my_result->fetchAll();
This code works as expected. However, if you attempt to use named parameters with an IN clause, the following code will not:
$in_array = 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(array(':in_values' => $in_values));
$my_results = $my_result->fetchAll();
Explanation:
PDO has difficulty handling IN clauses with arrays. Instead, you need to create a string with placeholders and insert it into the query, binding array values in the usual way.
Alternatives:
Using Positional Placeholders
Create a string with placeholders dynamically and insert it into the query:
$in = str_repeat('?,', count($in_array) - 1) . '?';
$sql = "SELECT * FROM my_table WHERE my_value IN ($in)";
$stm = $db->prepare($sql);
$stm->execute($in_array);
$data = $stm->fetchAll();
Using Named Placeholders
You can use the array_merge() function to join all variables into a single array, including named placeholders:
// Other parameters that are going into query
$params = ["foo" => "foo", "bar" => "bar"];
$ids = [1, 2, 3];
$in = "";
$i = 0; // Using an external counter because actual array keys could be dangerous
foreach ($ids as $item) {
$key = ":id" . $i++;
$in .= ($in ? "," : "") . $key; // :id0,:id1,:id2
$in_params[$key] = $item; // Collecting values into a key-value array
}
$sql = "SELECT * FROM table WHERE foo=:foo AND id IN ($in) AND bar=:bar";
$stm = $db->prepare($sql);
$stm->execute(array_merge($params, $in_params)); // Just merge two arrays
$data = $stm->fetchAll();The above is the detailed content of Why Doesn't PDO's IN Clause Work with Array Parameters, and How Can I Fix It?. For more information, please follow other related articles on the PHP Chinese website!
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