5 lessons
Entities and attributes — the nouns of a database
What an entity, entity set, and attribute are, and the different types of attributes you'll use when modeling any real-world system.
Relationships and cardinality
How entities connect to each other, relationship degree, and the four cardinality ratios that describe exactly how many entities can participate on each side.
Keys in the ER model
Super keys, candidate keys, primary keys, and how weak entities borrow a key from a stronger entity they depend on.
Weak entities, generalization, and specialization
A closer look at weak entities and identifying relationships, plus how the ER model expresses "is-a" hierarchies through generalization, specialization, and aggregation.
Converting an ER diagram into relational tables
The mechanical rules for turning entities, relationships, weak entities, and specialization hierarchies into actual relational tables.