Data modeling

The data model (MD) is an intelligent tool that allows you to formalize the COP using the language of definition D.
MD provide an opportunity to describe the semantics of the data (DM).
All MDs are based on the atomic unit D (AED), which is represented as the following tuple:
<Name of object, property of property, value of property, time>
The most difficult element is time.
As a rule, all MDs replace time with the ordering D, i.e. the process of the life of an object is determined by sequential recording it in some collection of D.
The main atomic element:
<Object name, property name, value property>
The simplest representation of elementary gaps and connections is the network structure, in which vertices are elements, and links are arcs.
The second method of communication between D is the distribution of D by categories.
D one category are called presumable.
Depending on the requirements for data categorization, the models are distinguished:

• strongly typed;
• weakly typed.

Strongly typed M - all D must be assigned to a certain category. All categories are homogeneous (homogeneous), i.e. All objects belonging to a category must have the same structure and properties.
Advantages: it is possible to build abstractions of the properties of D, i.e. build a theory based on categories that encapsulate (combine) the basic properties of D. All data are necessarily assigned to a category, this allows you to eliminate the inconsistency of data.
Weak-typed M - provide integration of D and categories, i.e. everyone is equal.
All commercial databases are strongly typed.

Data Model Definition (MD)

MD is a rule in accordance with which the data is structured.

MD (M) consist of a set of rules for generating data (G) and a set of rules for operations on data (O).

G is the language of the description of D, it defines the static properties of D, namely the permissible structures of D, objects and connections. (employee type is a category; category property: name, age, address; specific data - implementation).
Integrity constraints are set for each entity and each implementation must satisfy these constraints.
Thus, G rules are divided into two types:

• structure generation rules (GS).
• Rules for generating restrictions (GC).

Restrictions can be explicit - the concept of a key (employee number) and internal - the restriction of communication between objects.
The rules G generate multiple DB schemas; these schemas define specific DBs, with their structure and constraints.
The dynamic properties of the database are determined by the set of operations (O), this set is called the data manipulation language, they translate the database from one state to another.

Db life cycle

• Phase analysis.
  • Formulation and analysis of database requirements.
  • Conceptual design.
  • Select a database model.
  • Physical design.
• Phase of operation.
  • Implementation of the database on a specific database. Selection and justification of the DBMS.
  • Analysis of the functioning of the database, the effectiveness and support of the database.
  • Modification and adaptation of the database.

Conceptual Design (KP)

The main stages of KP:

• Definition of the main objects of design.
• Definition of sets characteristic for these objects.
• Definition of relationships between objects.
• Visualization of the conceptual model.
• Defining constraints for an object.