conceptual model
- Entity : something that exists objectively and can be distinguished from each other
- Attribute : a property of an entity
- Code (key) : a set of attributes that uniquely identifies an entity
- Entity type: abstract and describe similar entities with entity names and their attribute name sets
There are many types of connections between entities such as one-to-one, one-to-many, and many-to-many .
A representation of a conceptual model: the entity-relationship approach (ER model)
relational model
Each component of the relation must be an indivisible data item
| relational term | side table term |
| relationship name | Table Name |
| relational schema | table header (description of the table) |
| relation | (one) two-dimensional table |
| tuple | record or line |
| Attributes | List |
| property name | column name |
| attribute value | bad column value |
| weight | A column value in a record |
| non-normative relationship | Tables have tables (small tables are embedded in large tables) |