db_mysqli.php

$master_success = @mysqli_select_db($this->read_link, $database) or $this->error("[READ] Unable to select database", $this->read_link);                
if($this->write_link)
{
    $slave_success = @mysqli_select_db($this->write_link, $database) or $this->error("[WRITE] Unable to select slave database", $this->write_link);

    $success = ($master_success && $slave_success ? true : false);
}
else
{
    $success = $master_success;
}
return $success;