Is it possible to connect to two different mysql databases? - php

Question

I have 2 databases that I need to connect with but I don't know how to put the query in my code.
I have 2 pages of code. 1 for the form and the other to display the data after we have filled out the form. Will I need to put a new query on both pages or neither?
When I try to put a second connection on both pages, the whole page isn't working.
The connection I have made looks like this for both pages:
<?php
session_start();
include('conn.php');
include('connection2.php');
?>
For second database:
<?php
define('DB_HOST2','localhost');
define('DB_USER2','root');
define('DB_PASSWORD2','');
define('DB_NAME2','smile2');
$dbc = #mysql_connect(DB_HOST2,DB_USER2,DB_PASSWORD2) OR Die ('Could not connect to MySQL: '. mysql_error());
#mysql_select_db (DB_NAME2) OR Die ('Could not select database: '. mysql_error());
?>
For first database:
<?php
define('DB_HOST','localhost');
define('DB_USER','root');
define('DB_PASSWORD','');
define('DB_NAME','smile');
$dbc = #mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) OR Die ('Could not connect to MySQL: '. mysql_error());
#mysql_select_db (DB_NAME) OR Die ('Could not select database: '. mysql_error());
?>
How can I make #mysql_* change to:
<?php
//connect
mysql_connect("localhost", "user", "password");
//select first database
mysql_select_db("database_1");
//do query
mysql_query("SELECT * FROM `table` WHERE `field` = 1");
//select second database
mysql_select_db("database_2");
//do query on other database
mysql_query("SELECT * FROM `other_table` WHERE `field` = 2");
//you might wanna switch back to the first database
mysql_select_db("database_1");
?>

Answer 1

You can use the PHP function mysql_select_db to switch between databases. Like so:
<?php
//The preferred way:
//connect
mysqli_connect("localhost", "user", "password");
//select first database
mysqli_select_db("database_1");
//do query
mysqli_query("SELECT * FROM `table` WHERE `field` = 1");
//select second database
mysqli_select_db("database_2");
//do query on other database
mysqli_query("SELECT * FROM `other_table` WHERE `field` = 2");
//you might wanna switch back to the first database
mysqli_select_db("database_1");
//The old way
//connect
mysql_connect("localhost", "user", "password");
//select first database
mysql_select_db("database_1");
//do query
mysql_query("SELECT * FROM `table` WHERE `field` = 1");
//select second database
mysql_select_db("database_2");
//do query on other database
mysql_query("SELECT * FROM `other_table` WHERE `field` = 2");
//you might wanna switch back to the first database
mysql_select_db("database_1");
?>

Answer 2

<?php
class manageDB{
private $dbStatus = false;
private $mode = 'debug';
private $curCon = 'db1';
private $db = '';
private $con = '';
private $details = array(
'db1'=>array(
'server'=> '',
'user' => '',
'pass' => '',
'db' => ''
),
'db2'=>array(
'server'=> '',
'user' => '',
'pass' => '',
'db' => ''
)
);
//Init object
function __construct() {
$this->curCon = ($GLOBALS['isDebug']) ? 'db1' : 'db2';
}
public function defineDB($options, $type){
if(empty($type)){
$this->curCon = 'db1';
$this->details[$this->curCon]['server'] = $options['server'];
$this->details[$this->curCon]['user'] = $options['user'];
$this->details[$this->curCon]['pass'] = $options['pass'];
$this->details[$this->curCon]['db'] = $options['db'];
$this->con = null;
} else {
$this->curCon = $type;
}
$this->returnDB = FALSE;
if($this->dbStatus == TRUE) $this->open();
}
public function open(){
$this->con = mysql_connect($this->details[$this->curCon]['server'], $this->details[$this->curCon]['user'], $this->details[$this->curCon]['pass']);
if (!$this->con) { die('Could not connect: ' . mysql_error()); };
mysql_select_db($this->details[$this->curCon]['db'], $this->con);
$this->dbStatus = true;
}
public function close(){
mysql_close($this->con);
unset($this->connectStatus);
$this->dbStatus = false;
}
public function changeDB($db){
if($this->details[$this->curCon]['db'] != $db) mysql_select_db($db, $this->con);
$this->returnDB = TRUE;
return $this;
}
public function qry($query) {
$args = func_get_args();
if(count($args) > 1){
$query = array_shift($args);
$query = str_replace("?", "%s", $query);
$args = array_map('mysql_real_escape_string', $args);
array_unshift($args,$query);
$query = call_user_func_array('sprintf',$args);
}
$result = mysql_query($query);
//Check if we need to return to default table
if(isset($this->returnDB)){
mysql_select_db($this->details[$this->curCon]['db'], $this->con);
$this->returnDB = FALSE;
}
if($result){
return $result;
}else{
$error = "Error";
return $result;
}
}
public function checkStatus(){ echo $this->dbStatus; }
};
$db = new manageDB();
?>
Usage:
for normal operations use
$select = $db->query(...);
to switch database use
$select = $db->changeDB('db_name')->query(...);

Answer 3

easily done one step at a time, like here:
<?php
$link = mysql_connect("localhost", "mysql_user","mysql_password")
or die("Could not connect to MYSQL");
$selected_db = mysql_select_db('Database_Name', $link)
or die ('Sorry, could not connect to Database');
echo 'Connected successfully';
mysql_close($link);
?>
then the second one as:
<?php
$link = mysql_connect("localhost", "mysql_user","mysql_password")
or die("Could not connect to MYSQL");
$selected_db = mysql_select_db('Database_Name', $link)
or die ('Sorry, could not connect to Database');
echo 'Connected successfully';
mysql_close($link);
?>