"DB":{
         "Type":"AWS::RDS::DBInstance",
         "Properties":{
            "DBName":"TestDB",
            "Engine":"mysql",
            "EngineVersion":"5.7.21",
            "DBInstanceClass":"db.t1.micro",
            "DBInstanceIdentifier":"testdb",
            "MasterUsername":"root",
            "MasterUserPassword":"test#west#345",
            "AllocatedStorage":"100",
            "Iops":"1000",
            "BackupRetentionPeriod":"7",
            "DBSubnetGroupName":{
               "Ref":"DBSubnetGroup"
            },
            "MultiAZ":false,
            "PubliclyAccessible":false,
            "AutoMinorVersionUpgrade":false,
            "VPCSecurityGroups":[
               {
                  "Ref":"SecurityGroup"
               }
            ]
         }
      }