connecting to alternate database when primary database is down? - php

Question

$servername1 = "localhost1";
$username1 = "user1";
$password1 = "pwd";
$dbname1 = "dbs1";
$servername2 = "localhost2";
$username2 = "user2";
$password2 = "ped2";
$dbname2 = "dbs2";
// Create connection
$conn = new mysqli($servername1, $username1, $password1, $dbname1);
// Check connection
if ($conn->connect_error) {
$conn = new mysqli($servername2, $username2, $password2, $dbname2);
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);}
}
Can this type of connection be implemented?? when i implement this deliberately making an error in first database credentials i get a warning that Unknown MySQL server host 'localhost1'
and doesn't load the page. why is this not working?

Answer 1

I make a list of databases and then iterate through them and try to connect. It should be no problem using multiple databases. Using localhost1 and localhost2 (only localhost is possible which is 127.0.0.1) is not possible. You should use IP addresses.
Here is the code:
<?php
$Databases = array(
0 => array(
'db_kind' => 'postgres',
'host' => $server1[$server1["current"]]["host"],
'port' => $server1[$server1["current"]]["port"],
'db_name' => 'database1',
'username' => 'xxx',
'password' => 'yyy',
"type"=>DB_TYPE_3,
),
1 => array(
'db_kind' => 'postgres',
'host' => $server1[$server1["current"]]["host"],
'port' => $server1[$server1["current"]]["port"],
'db_name' => 'database2',
'username' => 'xxx',
'password' => 'yyy',
"type"=>DB_TYPE_2,
),
2 => array(
'db_kind' => 'postgres',
'host' => $server1[$server1["current"]]["host"],
'port' => $server1[$server1["current"]]["port"],
'db_name' => 'database3',
'username' => 'xxx',
'password' => 'yyy',
"type"=>DB_TYPE_1,
),
);
for($i=0;$i<count($Databases);$i++)
{
if($last_db_ind>=count($Databases)){
$last_db_ind=0;
}
if(($db =& db_connect($last_db_ind++))==false){
echo 'Connection failed for DB: '. $Databases["db_name"] . ', DB index: '.$last_db_ind;
continue;
}
?>

Answer 2

You should either use "localhost" or an IP address to connect to the SQL server. In your case it tries to connect to "localhost1" (as in you variable) which doesn't exists (unless you changed your host file). Try using IPs (127.0.0.1 for localhost and any other for the backup)
Cheers,
JCK

Answer 3

You Can try Ping first.
OR
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ")
" . $mysqli->connect_error;
}
OR
extension_loaded("mysql");