QAQ.

For such a long time I didn't read this book.

## Relational Model

In my opinion, the relational model is a mathematical model to describe the theory behind the RDBMS( Relational Database System), so it can represent some items or objects more clearly than sentences.

### Relation

Relation is just a table. And it has some rows and colomns.

### Attribute

In a relation, there are some colomns, and a named colomns is called an attribute.

### Domain

Each attribute must have some constraints to its value. So, the domain is the set of allowable values for one or more attributes.

### Tuple

It is a row of a relation.(or in a table)

### Relational database

A collection of normalized relations with distinct relation names. Normalized is explained as “appropriately structured”. Some….Kind of ? Maybe I can understand but can't tell.

### Other Terms

Degree, cardinality.