I am a marketing major, and I have to learn the basics by myself in my spare time.

The things in the book can't be said to be useless, but give you a theoretical system and a way of thinking, which can really guide you when it comes to practice. Therefore, read more books at school. I suggest you read more knowledge outside the marketing major, such as statistical analysis, such as industry white papers. .....

Practice more after work and see how what you have learned can be applied to practice.