How to Efficiently Bind an Array of Strings to a MySQL WHERE IN(?) Clause Using PHP's mysqli Prepared Statements?

Binding an Array of Strings to a WHERE IN(?) Clause

Binding an array of values to the WHERE IN(?) clause is a common MySQL task. When using PHP's mysqli prepared statements, it can be challenging to achieve if you're not familiar with the limitations and nuances of the bind_param() function.

The Problem

You may encounter issues when trying to bind an array of values to the IN(?) clause using bind_param(), resulting in an unsuccessful execution.

The Solution

There are different ways to approach this task, depending on the version of PHP you are using:

PHP 8.2 and Above

• execute_query() function: This function allows you to directly pass an array of values to IN(?). It simplifies the process with a single line of code.

PHP 8.1

• Passing an array to execute(): In PHP 8.1, you can pass an array directly to execute() for prepared statements, making it simpler to bind multiple values.

Earlier PHP versions

For older versions, a more elaborate approach is necessary:

1. Create a string with as many question marks (?) as the number of elements in the array.
2. Add the string with placeholders to the query string.
3. Create a types string using str_repeat() to bind data with the correct types (e.g., 's' for strings).
4. Bind the array elements to the statement using the argument unpacking operator (...) in bind_param().
5. Execute the statement and retrieve the result data.

Example Code

Here's an example using the earlier PHP versions' approach:

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

By understanding these approaches, you can efficiently bind an array of strings to a WHERE IN(?) clause using mysqli prepared statements, ensuring successful execution of your queries.

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