無論你在 CS /DS/AI/ML spectrum上的哪個地方，必須很熟練和深入理解。
來一段關係數據庫之歌：
Simple and relentless
Conceptualize all information in terms of relations (rows, columns, values)
Whenever you say anything, say it in relations Whenever you do anything, do it with relations Whenever you talk, talk in relations Whenever you think, think in relations
Rows, columns, and values. Nothing else. Ever!
Upload your data in rows and columns, query your data in rows and columns, receive your query results in rows and columns, only buy software that works on rows and columns, eat, drink and sleep rows and columns
Pay no attention to how the information is stored— that’s not your problem!
relations, relations, relations, relations
The End！
