Design fundamentals

What Is a Database Index?

by Michał Kołodziejski
7 Oct 2014 Sooner or later there comes a moment when database performance is no longer satisfactory. One of the very first things you should turn to when that happens is database indexing. This article will give you a general overview on what indexes are without digging into too much detail. We’ll discuss additional database index topics in future articles. In general, a database index is a data structure used to improve queries execution time.
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Design fundamentals

UML Notation

by Patrycja Dybka
6 Aug 2014 UML is popular for its notations. We all know that UML is for visualizing, specifying, and documenting the components of software and non software systems. What’s more, UML has many types of diagrams which are divided into two categories. Some types represent structural information, others general types of behaviors. Among these, there is one that is commonly used for entity relationship diagrams. In UML, an entity is represented by a rectangle:
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Design fundamentals

Arrow Notation

by Patrycja Dybka
5 Aug 2014 Arrow notation has become one of the less recognized notations in entity relationships diagrams in recent years. Let’s discuss its elements. Entity and relationships As you can see below, an entity is always represented by a rectangle, which is common to most notations (there isn’t a distinction if it is dependent or independent entity). Relationships and cardinality are represented by various combinations of arrows as the diagram below presents.
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Design fundamentals

IDEF1X Notation

by Patrycja Dybka
4 Aug 2014 IDEF1X (Integration DEFinition for Information Modeling) is a method for designing relational databases with a syntax that supports constructs in developing conceptual schema. Not everyone knows that this notation has an interesting history. Indeed, the need for semantic data models was first recognized by the U.S. Air Force in the mid-1970s. As a result, the ICAM Program came into being (It identified a need for better analysis and communication techniques for people involved in improving manufacturing productivity), that later developed a series of techniques known as the IDEF; IDEF1X being one of them.
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Design fundamentals

Chen Notation

by Patrycja Dybka
2 Aug 2014 Continuing our trip through different ERD notations, let’s review the Chen ERD notation. Peter Chen, who developed entity-relationship modeling and published his work in 1976, was one of the pioneers of using the entity relationship concepts in software and information system modeling and design. The Chen ERD notation is still used and is considered to present a more detailed way of representing entities and relationships. Entities An entity is represented by a rectangle which contains the entity’s name.
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Design fundamentals

Barker’s Notation

by Patrycja Dybka
1 Aug 2014 When looking at different kinds of ERD notations, it is hard not to come across Barker’s ERD notation, which is commonly used to describe data for Oracle. Richard Barker and his coworkers developed this ERD notation while working at the British consulting firm CACI around 1981, and when Barker joined Oracle, his notation was adopted. Let’s take a closer look at Barker’s syntax. The most important components in the ERD diagram are:
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Design fundamentals

ERD Notations in Data Modeling

by Patrycja Dybka
31 Jul 2014 An entity relationship diagram (ERD) is a diagram that defines the structure of database instances. Choosing which notation to use is typically left up to personal preference or conventions. Here, you can find some useful information about each notation: Part 1 – Barker’s Notation Part 2 – Chen Notation Part 3 – IDEF1X Notation Part 4 – Arrow Notation Part 5 – UML Notation Part 6 – Crow’s Foot Notation Which ERD notation are you using?
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Design fundamentals

How to Model Inheritance in a Relational Database

by Patrycja Dybka
28 Jul 2014 In the process of designing our entity relationship diagram for a database, we may find that attributes of two or more entities overlap, meaning that these entities seem very similar but still have a few differences. In this case, we may create a subtype of the parent entity that contains distinct attributes. A parent entity becomes a supertype that has a relationship with one or more subtypes. First, let’s take a closer look at a simple class diagram.
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Design fundamentals

N-ary relationship types

by Patrycja Dybka
15 Jul 2014 When we design a database, we draw an entity relationship diagram (ERD). It helps us understand what kind of information we want to store and what kind of relationships there are. It is imperative that this diagram is easy to read and understand. The number of entities in a relationship is the arity of this relationship. The aim of this article is to give some examples and show how big an impact the arity of relationships has on not only the readability of the diagram, but also the database itself.
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Design fundamentals

Database Design 101

by Vertabelo Team
10 Apr 2014 In this video you will learn how to start creating your database model. You will find out why nouns are important and how you should handle them when creating a database model. If you want to learn more, read our beginner tutorial on how to create a database model. iframe.video-plugin { width: 735px; height: 415px; border: 0px solid #CCC; margin: 0px; } @media all and (max-width: 767px) { iframe.
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