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.
How to create a new SQL database using a SQL database creator?
You can manually write SQL scripts in your favorite SQL editor and execute individual SQL commands directly on the connected database. However, another option is to use a data modeling tool in which you design the database structure visually, using an ER diagram.… Read the rest
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
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
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:
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 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
Many-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 relationship between the entities student and course. Each student can have multiple courses and each course is for multiple students.… Read the rest
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 order and item. Each order may have multiple items, but a product (e.g.,… Read the rest
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
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