Modeling and data analysis.

Data modeling Technique to organize and document the data of a system. Sometimes called database modeling.

Relationship entity diagram (ERD) A data model that uses various notations to illustrate the data in terms of the entities and relationships described by that data.

Entity Classes of people, places, objects, events or concepts about which we need to capture and store data.

Entity Instance Individual occurrence of an entity.

Property attribute or descriptive characteristic of an entity. Synonyms include element, property and field.

Composite attribute An attribute that consists of other attributes. The synonyms in the different data modeling languages ​​are numerous: concatenated attribute, attribute

compound and data structure.

Data type Property of an attribute that defines what values ​​the attribute can legitimately adopt.

Domain Property of an attribute that defines what values ​​the attribute can legitimately adopt.

Default value Value that will be registered if the user does not specify a value.

Key Attribute or group of attributes that adopts a unique value for each entity instance. Sometimes it is called an identifier.

Concatenated key Group of attributes that uniquely identify the instance of an entity. Its synonyms are composite key and combined key.

Candidate key One of several keys that can serve as the primary key of an entity. Also called candidate identifier.

Primary key A candidate key that will be very commonly used to uniquely identify an individual entity instance.

Alternative key A candidate key that is not selected to become a primary key. A synonym is a secondary key.

Criterion (s) of subsets Attribute (s) whose finite values ​​divide the instances of the entity into subsets. Sometimes called reverse input.

Relationship Natural business association between one or more entities.

Cardinality Minimum and maximum number of occurrences of an entity that can be related to an individual occurrence of the other entity.

Degree Number of entities that participate in a relationship.

Recursive relationship A relationship that exists between two instances of the same entity.

Associative entity Entity that inherits its primary key from more than any other entity.

Foreign key Primary key of an entity that is used in another entity to identify the instances of a relationship.

Child Entity A data entity that derives one or more attributes from another entity, called a parent. In a one-to-many relationship the son is the entity on the side of the “many”.

Parent Entity A data entity that brings one or more attributes to another entity, called a child. In a one-to-many relationship the parent is the entity on the “one” side.

Relationship without identification Relationship in which each participating entity has its own independent primary key.

Generalization A concept according to which attributes that are common to various entity types are grouped in their own entity.

Supertype Entity whose instances store attributes that are common to one or more entity subtypes.

Subtype Entity whose instances can inherit common attributes from the supertype of their entity.

Data model of the application Data model for a complete individual information system.

Context data model Data model that includes entities and relationships, but not attributes.

Key-based data model A data model that includes entities and relationships with precise cardinalities that transform non-specific relationships into associative entities, and that also include primary and alternate keys.

Integral data model Data model that includes all entities, attributes, relationships, subset criteria and precise cardinalities.

Metadata Data about the data.

Smart key Business code whose structure communicates data about an entity instance.

Data analysis Technique that is used to improve a data model for its implementation as a database.

Standardization Data analysis technique that organizes data in groups to form non-redundant, stable, flexible and adaptive entities.

1. First normal form (1FN) Entity whose attributes have only one value for an individual instance of that entity.
2. Second normal form (2FN) Entity whose non-primary key attributes depend on the complete primary key.
3. Third normal form (3FN) Entity whose non-primary key attributes do not depend on any other attributes with primary key.

Derived attribute An attribute whose value can be calculated from other attributes or derived from the values ​​of other attributes.

Transitive dependence When the value of an attribute that is not a key depends on the value of another attribute that is not key by other means than it is not.