Specifying the VPC for your Amazon RDS DB Instance

You can now easily change the Amazon Virtual Private Cloud (Amazon VPC) used by your Amazon RDS DB instance. You can specify a new VPC for an existing DB instance deployed in Single-AZ configuration by using the Amazon RDS Management Console, the Amazon RDS API, or the AWS Command Line Tools. In addition, if you are running your DB instance on the EC2-Classic environment, you can switch to the EC2-VPC environment by modifying your existing DB instance. If your AWS account was created before 2013-12-04, you are potentially running RDS on the EC2-Classic environment.
Quelle: aws.amazon.com