Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: Poorly written book

This is one of the worst books ever written about database systems. The writing is unclear and poorly written. Examples are presented too complex for readers to clearly understand what is going on. It even refers to examples many pages back where you have to flip back and forth and gets repetitive. There is also no clear drawings or diagrams that help the reader understand what the author is trying to point out. Overall a very poor book and not worth the time spent in reading and figuring out what is going on.