How to Bind an Array of Strings to a MySQLi WHERE IN (?) Clause?

Binding an Array of Strings in a WHERE IN (?) Clause with MySQLi

When working with MySQLi prepared statements, it's essential to understand how to bind an array of values to a WHERE IN (?) clause. This article provides a comprehensive guide to solving this problem effectively.

The Challenge

The goal is to dynamically bind an array of city names to a WHERE IN clause in a MySQLi prepared statement. However, the code provided initially fails to execute due to incorrect binding of the array.

Binding an Array of Strings

Several approaches exist for binding an array of strings. Let's explore the methods available:

1. execute_query() Function (PHP 8.2)

The simplest solution is available in PHP 8.2 with the introduction of the execute_query() function. This method allows passing both the SQL statement and an array of values to be bound in one go.

$array = ['Nashville', 'Knoxville'];
$parameters = str_repeat('?,', count($array) - 1) . '?';
$sql = "SELECT name FROM table WHERE city IN ($parameters)";
$result = $mysqli->execute_query($sql, $array);

2. Array into execute() (PHP 8.1)

In PHP 8.1, you can pass an array directly to the execute() method without the need for placeholders or binding.

$stmt = $mysqli->prepare($sql);
$stmt->execute($array);

3. Prepare/Bind/Execute for Older Versions

For versions prior to PHP 8.1, the following steps are required:

• Create a string of placeholders (e.g., "?,?" for an array of two values).
• Add this string to the query.
• Prepare the statement.
• Create a string of types (e.g., "ss" for two string values).
• Bind the array values using the argument unpacking operator.

$types = str_repeat('s', count($array));
$stmt->bind_param($types, ...$array);

Example:

$array = ['Nashville', 'Knoxville'];
$in = str_repeat('?,', count($array) - 1) . '?';
$sql = "SELECT name FROM table WHERE city IN ($in)";
$stmt = $mysqli->prepare($sql);
$stmt->bind_param(str_repeat('s', count($array)), ...$array);
$stmt->execute();
$result = $stmt->get_result();

By following these approaches, you can effectively bind an array of strings to a WHERE IN (?) clause in MySQLi prepared statements.

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