mysql_* to MySQLi - php

Question

I recently learned that mysql_* has been depreciated and i have a quick question on how to rewrite something.
$db = mysql_connect("localhost","root","PASSWORD");
if(!$db) die("Error connecting to MySQL database.");
mysql_select_db("FormData" ,$db);
I have tried rewriting it like this...
$mysqli = new mysqli("localhost", "root", "PASSWORD", "FormData", $db);
if(!$db) die("Error connecting to MySQL database.");
But when it posts my form i get the "Error connecting to MySQL database." error. I was able to fix it by just using this but i wanted to know how to add in the Error connecting.
$mysqli = new mysqli("localhost", "root", "PASSWORD", "FormData");
Any help would be great as i try to learn all of the new MySQLi stuff!

Answer 1

PHP website
Straight from php.net
<?php
$mysqli = new mysqli('localhost', 'fake_user', 'my_password', 'my_db');
// Works as of PHP 5.2.9 and 5.3.0.
if ($mysqli->connect_error) {
die('Connect Error: ' . $mysqli->connect_error);
}
?>
Edit:
The below will also allow you to do it your way.
$mysqli = mysqli_connect('localhost', 'fake_user', 'my_password', 'my_db');
Then you can:
if (!$mysqli) {
//handle the error
}
Consider PDO if possible. They are kind similar to me.

Answer 2

$mysqli = new mysqli("localhost", "root", "PASSWORD", "FormData", $db);
if(!$db) die("Error connecting to MySQL database.");
should be
$mysqli = new mysqli("localhost", "root", "PASSWORD", "FormData");
if($mysqli->connect_error) die("Error connecting to MySQL database.");
the parameters for mysqli() are:
[ string $host = ini_get("mysqli.default_host") [, string $username = ini_get("mysqli.default_user") [, string $passwd = ini_get("mysqli.default_pw") [, string $dbname = "" [, int $port = ini_get("mysqli.default_port") [, string $socket = ini_get("mysqli.default_socket") ]]]]]]
Not sure why you were trying to use the $db variable to set the port for the connection and then checking if the port variable is true...
For future reference the best place to look first, would be the docs
EDIT
As #Touch pointed out, you must check if error exists and not just that object exists. Edited code to reflect this.

Answer 3

Using mysqli:
define('DB_HOST', 'localhost');
define('DB_NAME', 'some_database_name');
define('DB_USER', 'some_user');
define('DB_PASS', 'some_password');
$Connection = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
if (!$Connection->connect_errno)
{
//do your prepared stuffs
}
else
{
die("Database Connection error:".$Connection->connect_error);
}
or using PDO
try
{
$PDOConnection = new PDO('mysql:host='.DB_HOST.';dbname='.DB_NAME.'', DB_USER, DB_PASS);
$PDOConnection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
//do your prepared stuffs
$PDOConnection = null;
}
catch(PDOException $e)
{
die('ERROR: ' . $e->getMessage());
}

Answer 4

I wrote a class called better_mysqli that extends mysqli making it easier to use.
The following example shows the answer to your question and also shows basic usage of the better_mysqli class. You can view a detailed example with lots of comments here: detailed usage of better_mysqli
<?php
include_once('better_mysqli.php'); // can be obtained from: http://pastebin.com/ATyzLUfK
// THIS NEXT PART ANSWERS YOUR QUESTION
// THIS NEXT PART ANSWERS YOUR QUESTION
// THIS NEXT PART ANSWERS YOUR QUESTION
// THE ONLY DIFFERENCE IN THE CONNECTION WHEN USING better_mysqli AND mysqli
// is $mysqli = new better_mysqli(...) and $mysqli = new mysqli(...)
// == Instantiate the mysqli database object (aka open the database) ==
$mysqli = new better_mysqli('your_server', 'your_user', 'your_pass', 'your_db_name');
if (mysqli_connect_errno()) {
error_log(sprintf("Can't connect to MySQL Server. Errorcode: %s\n", mysqli_connect_error()));
exit;
}
// == select example ==
unless( $sth = $mysqli->select('select * from table1 where col1=? and col2=?', $row, array('col1_placeholder_value', 'col2_placeholder_value'), $debug_level=0, $verbose_debug_output)){
if($debug_level>0){ echo $verbose_debug_output;}
// .. do your error handling here
}
while($sth->fetch()){
echo $row['col1'] .', '. $row['col2'] .', and '. $row['col_etc'] .' are accessed like that.<br>';
}
// == insert example ==
$statement = "insert into table1 (col1, col2, date_col, col_etc) values (?, ?, NOW(), ?)";
unless( $mysqli->insert($statement, array('col1_insert_value', 'col2_insert_value', 'col_etc_value'), $debug_level=0, $verbose_debug_output, $id_of_new_record) ){
if($debug_level>0){ echo $verbose_debug_output;}
// .. do your error handling here
}
// == update example ==
unless($mysqli->update("update table1 set col1=? where col2=?", array('col1_value', 'col2_value'), $debug_level=0, $verbose_debug_output) ){
if($debug_level>0){ echo $verbose_debug_output;}
// .. do your error handling here
}
// == delete example ==
unless( $mysqli->delete("delete from table1 where col1=? where col2=?", array('col1_value', 'col2_value'), $debug_level=0, $verbose_debug_output) ){
if($debug_level>0){ echo $verbose_debug_output;}
// .. do your error handling here
}
// in all cases statements are prepared just once and cached so if you reuse any statement the already prepared statement handle is automatically used
?>