你可以使用AWS CloudFormation来创建一个数据库实例，并为该实例创建一个IAM角色。以下是一个示例解决方案：

Resources:
  MyDatabaseInstance:
    Type: "AWS::RDS::DBInstance"
    Properties:
      Engine: "mysql"
      DBInstanceIdentifier: "my-database-instance"
      AllocatedStorage: "20"
      DBInstanceClass: "db.t2.micro"
      MasterUsername: "admin"
      MasterUserPassword: "admin123"
      VPCSecurityGroups:
        - !Ref MySecurityGroup
      DBSubnetGroupName: "my-db-subnet-group"
      PubliclyAccessible: false
      Tags:
        - Key: "Name"
          Value: "MyDatabaseInstance"

  MyDatabaseInstanceRole:
    Type: "AWS::IAM::Role"
    Properties:
      RoleName: "MyDatabaseInstanceRole"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "rds.amazonaws.com"
            Action: "sts:AssumeRole"

  MyDatabaseInstancePolicy:
    Type: "AWS::IAM::Policy"
    Properties:
      PolicyName: "MyDatabaseInstancePolicy"
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Action:
              - "rds:CreateDBInstance"
              - "rds:DeleteDBInstance"
              - "rds:DescribeDBInstances"
            Resource: "*"
      Roles:
        - !Ref MyDatabaseInstanceRole

上述代码示例中，我们创建了一个数据库实例（MyDatabaseInstance），并为该实例创建了一个IAM角色（MyDatabaseInstanceRole）。这个角色具有允许执行RDS相关操作的权限。

请注意，这只是一个示例解决方案，你需要根据你的具体需求和环境进行调整和修改。