What function can be used to determine the number of result rows returned by a database query in PHP?

To determine the number of result rows returned by a database query in PHP, you can use the `mysqli_num_rows()` function. This function returns the number of rows in a result set. You can call this function after executing a SELECT query to get the total number of rows returned by the query.

// Assuming $conn is your database connection and $query is your SELECT query

$result = mysqli_query($conn, $query);
$num_rows = mysqli_num_rows($result);

echo "Number of rows returned: " . $num_rows;