Duplicate entry '2147483647' for key 'PRIMARY' - php

Question

Based on what I've read here and on the web, you get this error if you try to store an integer > INT's maximum signed value; 2147483647. As you can see below, I used bigint(20) for user_id. So, I don't know why I'm getting this error.
CREATE TABLE IF NOT EXISTS `users` (
`user_id` bigint(20) unsigned NOT NULL,
`screen_name` varchar(20) NOT NULL,
`name` varchar(20) DEFAULT NULL,
`profile_image_url` varchar(200) DEFAULT NULL,
`created_at` datetime NOT NULL,
`followers_count` int(10) unsigned DEFAULT NULL,
`friends_count` int(10) unsigned DEFAULT NULL,
`statuses_count` int(10) unsigned DEFAULT NULL,
`last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`user_id`),
KEY `user_name` (`name`),
KEY `last_update` (`last_update`),
KEY `screen_name` (`screen_name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
The php script that handles the insertion:
/* Prepare an insert statement */
$query = "INSERT INTO users (user_id, screen_name, name, profile_image_url, created_at, followers_count, friends_count, statuses_count) VALUES (?,?,?,?,?,?,?,?)";
$stmt = $mysqli->prepare($query);
$stmt->bind_param("issssiii", $user_id, $screen_name, $name, $profile_image_url, $created_at, $followers_count, $friends_count, $statuses_count);
/* Execute the statement */
$stmt->execute()
FYI: the purpose of this script & table is to store some of Twitter's users data

Answer 1

INT has a maximum signed value of 2147483647. Any number greater than that will be truncated to that value. What you need to do is change that column to be a user_id varchar(20) unsigned NOT NULL, which will hold strings of up to 20 characters since cards numbers are strings and not actually numbers (you don't do math with the). You also should remove AUTO_INCREMENT as that is not a value you will be incrementing.