Data Base week2_2

Important points

• repetition,redundant (同一項目の重複を避ける)
• referential(参照する)
  
• integrity (完全性)
  

Anomalies

• Insert
• Update
• Delete

Primary key (unique key)
Foreign key (to refer from other tables)
Composite key(the key is made up of more than one key)

Homework
word excise file