Crow’s foot notation in ER diagram

Use crows foot notation to represent relationships between entities in an entity relational diagram. Entities are connected by lines, and symbols at the beginning or end of the line describe cardinality.

Relationship types and cardinality:

Symbols in crow’s foot notation

A crow’s foot graphics represents “many” or “infinite”.… Read the rest

NoSQL data modeling

Data modeling is the process of visually creating a graphical representation of a system or database. In the case of relational databases, we can mention the creation of entity-relational diagrams in which entities, attributes and relationships between entities are displayed. (Read more information about ER diagrams).

Advantages of data modeling

  • Fewer design and development errors
  • Easy and fast design, especially in the early stages of development
  • Better communication between team members
  • Time saving
  • Lower development costs
  • and many others

MongoDB schema design and noSQL database modeling

But what is the advantage of data modeling when we talk about noSQL databases?… Read the rest

What is Entity Relationship Diagram (ERD)?

Entity relationship diagram describes the structure of the database. The entity relationship diagram shows entities (tables in relational databases) and relationships between tables that exist in the database. For a good database design, it is very important to have an entity relationship diagram.

In an entity relationship diagram, the basic elements are:

  • Entities (tables)
  • Attributes (table columns)
  • Relationships (relationships between tables)

Why create entity relational diagrams?

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One-to-one relationships

One to many relationship is a type of cardinality that refers to a relationship between two entities in an entity relational diagram (between two tables in a database). A simple example would be a binding between the entities person and birth_certificate. Each person must have their own birth certificate.

Graphically, the one to one relationship is shown as follows:

one-to-one relationship

One-to-one relationships in Moon Modeler

How it works in version 4.2:

Every time you create a new relationship between tables, a one-to-many relationship is created.… Read the rest

How to set schema validation rules for fields in a project for MongoDB

In Moon Modeler, you can easily design MongoDB database structures and generate scripts for schema validation. Many schema validation rules are accessible directly in the user interface, and additional rules can be defined textually.

Let’s see how to set the validation to the minimum and maximum value, for example. As an example, let’s use the “students” collection, in which we have defined the fields “name“, “year” and “major“.… Read the rest

MongoDB vs PostgreSQL

Making a comparison of document-based database systems like MongoDB and traditional relational databases like PostgreSQL is not a simple task. In fact, it is impossible to recommend one database platform, because everything depends on your requirements and the goals you wish to achieve. For some use cases, MongoDB can be the preferred solution, for many other use cases PostgreSQL can be the better option.… Read the rest