br1.go

type Database interface {
    Insert(data interface{}) error
    Retrieve(id string) (interface{}, error)
}

type MySQL struct {
    connection *sql.DB
}

func (m *MySQL) Insert(data interface{}) error {
    // insert data into MySQL
}

func (m *MySQL) Retrieve(id string) (interface{}, error) {
    // retrieve data from MySQL
}

type MongoDB struct {
    session *mgo.Session
}

func (m *MongoDB) Insert(data interface{}) error {
    // insert data into MongoDB
}

func (m *MongoDB) Retrieve(id string) (interface{}, error) {
    // retrieve data from MongoDB
}