PHP: How can I give MySQL table a unique ID with this script?

<?php


$databasehost = "localhost"; 
$databasename = ""; 
$databasetable = ""; 
$databaseusername=""; 
$databasepassword = ""; 
$fieldseparator = ","; 
$lineseparator = "\n";
$enclosedbyquote = '"';
$csvfile = "db-core/feed/csv/csv.csv";

if(!file_exists($csvfile)) {
    die("File not found. Make sure you specified the correct path.");
}

try {
    $pdo = new PDO("mysql:host=$databasehost;dbname=$databasename", 
        $databaseusername, $databasepassword,
        array(
            PDO::MYSQL_ATTR_LOCAL_INFILE => true,
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        )
    );
} catch (PDOException $e) {
    die("database connection failed: ".$e->getMessage());
}

$pdo->exec("TRUNCATE TABLE `$databasetable`");

    $affectedRows = $pdo->exec("
    LOAD DATA LOCAL INFILE ".$pdo->quote($csvfile)." REPLACE INTO TABLE `$databasetable`
    FIELDS OPTIONALLY ENCLOSED BY ".$pdo->quote($enclosedbyquote)."
     TERMINATED BY ".$pdo->quote($fieldseparator)." 
    LINES TERMINATED BY ".$pdo->quote($lineseparator)." 
    IGNORE 1 LINES");

echo "Loaded a total of $affectedRows records from this csv file.\n";

?>