Invalid Data Source Name - Connection to MySQL with php, PDO and DSN - php

Question

This script
<?php
/* Connect to a MySQL database using driver invocation */
$dsn = 'mysqldg';
$user = 'odbc_dg';
$password = '999999999';
try {
$dbh = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}
?>
gives the error *Connection failed: invalid data source name*
I have created an entry in /etc/odbc.ini as follows:
[mysqldg]
Description = DGDB
Driver = mysql537
Database = dg1
Servername = 99.99.99.99
UID = odbc_dg
PWD = 999999
SSLKeyFile = /etc/mysql/ssl/ck.pem
SSLCertFile = /etc/mysql/ssl/cc.pem
SSLCAFile = /etc/mysql/ssl/c1.pem
/etc/odbcinst.ini has the following entry:
[mysql537]
Description = MySQL driver for Plesk
Driver = /usr/lib/odbc2/lib/libmyodcb5w.so
Setup = /usr/lib/odbc2/lib/libmyodbc5w.so
The entry in odbcinst.ini works with a non-DSN connection.
I'm obviously missing something, can anyone help? Thanks.
UPDATED....
I have tried Your Common Sense's code as follows:
<?php
$host = '46.99.199.199';
$db = 'dg';
$user = 'odbc_dg';
$pass = '999999';
$charset = 'utf8mb4';
$options = array(
PDO::MYSQL_ATTR_SSL_KEY => '/etc/mysql/ssl/ck.pem',
PDO::MYSQL_ATTR_SSL_CERT => '/etc/mysql/ssl/cc.pem',
PDO::MYSQL_ATTR_SSL_CA => '/etc/mysql/ssl/c1.pem'
);
$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
try {
$pdo = new PDO($dsn, $user, $pass, $options);
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}
?>
... but I get a connection fail message - Connection failed: SQLSTATE[HY000] [2002]
I think the problem is that the keys I have supplied only work with ODBC
For example this code, which uses odbc_connect works....
<?php
ini_set ('error_reporting', E_ALL);
ini_set ('display_errors', '1');
error_reporting (E_ALL|E_STRICT);
$user = "odbc_dg";
$pass = "99999";
$connection = "Driver= {mysql537};Server=46.99.199.199;Database=dgdb;UID=dgdb;PWD=999999;sslca=/etc/mysql/ssl/c1.pem;sslkey=/etc/mysql/ssl/ck.pem;sslcert=/etc/mysql/ssl/cc.pem";
$con = odbc_connect($connection, $user, $pass);
$sql="SELECT Id from stk_item";
$rs=odbc_exec($con,$sql);
if (!$rs) {
exit("Error in SQL");
}
echo "<table><tr>";
echo "<th>Companyname</th>";
echo "<th>Contactname</th></tr>";
while (odbc_fetch_row($rs)) {
echo odbc_result($rs, "Id"), "\n";
}
odbc_close($con);
echo "</table>";
?>
My problem is that I want to connect to the remote database via pdo because that's the only type of connection allowed in the Drupal synchronising code.