update query for unique column - php

Question

This query change only the name, I want change the username too...
<?php
define('HOST', 'localhost');
define('USERNAME', 'root');
define('PASSWORD', '');
define('DATABASE', 'mydb');
$mysqli = new mysqli(HOST, USERNAME, PASSWORD, DATABASE);
$query = "CREATE TABLE users (id INT UNSIGNED NOT NULL AUTO_INCREMENT, username VARCHAR(50) NOT NULL, name VARCHAR(50) NULL, PRIMARY KEY (id), UNIQUE(username)) ENGINE = MyISAM";
if ($mysqli->query($query)) {
$query = "INSERT INTO users (id, username, name) VALUES (1, 'user1', 'name1')";
if ($mysqli->query($query)) {
$query = "UPDATE users SET username = 'user_1', name = 'name_1' WHERE id = 1";
if ($mysqli->query($query)) {
$query = "SELECT id, username, name FROM users WHERE id = 1";
$result = $mysqli->query($query);
while ($row = $result->fetch_assoc()) {
echo 'id = ' . $row['id'] . ', username = ' . $row['username'] . ', name = ' . $row['name'];
}
$result->free();
}
}
}
$mysqli->close();
?>
In this example:
Started as [1, user1, name1]
Changed to [1, user1, name_1]
Instead of [1, user_1, name_1]
There is no way to update UNIQUE columns?

Answer 1

Your script won't run (table creation) when reloading it (only on the first/initial execution), since your table already exists and MySQL is failing on you silently, since you're not checking for errors.
Sidenote: You may have slightly modified your script and then ran it after.
Having included the following debugging code at the top of your script, you would have been thrown errors about it and is crucial when debugging during development before going live:
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
// rest of your code
Therefore, you can only run that script once. You need to either test it again with a new table name, or remove the table creation code.
You can also check if the table exists.
References:
http://dev.mysql.com/doc/refman/5.7/en/create-table.html
https://dev.mysql.com/doc/refman/5.5/en/replication-features-create-if-not-exists.html
A quick example:
CREATE TABLE IF NOT EXISTS `test`
You can also use UPDATE IGNORE table ... syntax (not to be used with your present table creation codes though):
http://dev.mysql.com/doc/refman/5.7/en/update.html
and INSERT IGNORE INTO table
https://dev.mysql.com/doc/refman/5.5/en/insert.html
Now your entire code (as a rewrite) would look like this:
$query = "CREATE TABLE IF NOT EXISTS users
(id INT UNSIGNED NOT NULL AUTO_INCREMENT,
username VARCHAR(50) NOT NULL,
name VARCHAR(50) NULL,
PRIMARY KEY (id),
UNIQUE(username))
ENGINE = MyISAM";
if ($mysqli->query($query)) {
$query = "INSERT IGNORE INTO users (id, username, name) VALUES (1, 'user1', 'name1')";
if ($mysqli->query($query)) {
$query = "UPDATE IGNORE users SET username = 'user_1', name = 'name_1' WHERE id = 1";
if ($mysqli->query($query)) {
$query = "SELECT id, username, name FROM users WHERE id = 1";
$result = $mysqli->query($query);
while ($row = $result->fetch_assoc()) {
echo 'id = ' . $row['id'] . ', username = ' . $row['username'] . ', name = ' . $row['name'];
}
$result->free();
}
}
}
There is no way to update UNIQUE columns?
Yes, with UPDATE IGNORE table ....
http://dev.mysql.com/doc/refman/5.7/en/update.html
However and with your present code, it will fail on the INSERT, since that is being executed before the UPDATE.
Think logically and you will see what is going on here.