Tag: Data Modeling

Lessons I’ve Learned from Years of Data Modeling

With age comes wisdom. Take it from someone who has spent a few decades dealing with databases, data models, IT guys, users, and software projects. “The greatest teacher failure is”, Master Yoda said. Decades of making mistakes with databases and data models – and learning from these mistakes – has proved to me that he was right. Yoda also said: “Always pass on what you have learned”. So here I am, passing on some of the lessons I’ve learned from tripping many times over the same data modeling stones.

Why Do You Need Data Modeling?

You need data modeling to save yourself or your organization lots of money, hours, and issues. Read on to find out how data models do its magic. Data modeling is the process of creating a conceptual view of the information a database contains or should contain. As a result of this process, a data model is created, giving form to data objects (all those entities for which information is to be stored), the associations or relationships among them, and rules or restrictions that govern the information that enters the database.

Top 19 Database Modeling Interview Questions

Do you have a database modeling interview coming up? Make sure to prepare to give yourself the best chance of getting the job! Find out what you’ll be asked in addition to “What are your strengths and weaknesses?” and “Where do you see yourself in five years?” So, you’re applying for a data modeling position...congratulations! It is a challenging job that involves great responsibility. Data modelers create a solid foundation for the information systems that manage the vital data of an organization.

Questions to Ask Business Users When Creating a Data Model

Data modeling is the process of creating a structure to store data. Database modeling creates a model of your database; it captures information about the data that must be stored for an application. Applications are tools that implement some sort of business logic, so if we are creating a model of the data required by some application, then data modeling must start with collecting business requirements. If you're unsure about the steps involved in the database design process, I refer you to other articles like the description of database design steps and tips for better database design.

How to Model Inheritance in a Database

Three ways to implement inheritance in a database using the Vertabelo data modeler. Inheritance is a common modeling technique used in modern software development. In data modeling, you can use inheritance in the logical model creation process. However, implementing inheritance in a physical database model is not straightforward; standard SQL does not provide inheritance statements for physical implementation. In this article, we will cover three basic strategies used to implement inheritance in a relational  database.

What Is a One-to-One Relationship in a Database?

What is a one-to-one relationship in data modeling? How do you implement this relationship in a database? The examples in this article will answer these questions. There are three types of relationships between entities (tables) in data modeling: One-to-many relationships (also denoted as 1:M). Many-to-many relationships (M:N). One-to-one relationships (1:1). The most common type of relationship is a one-to-many relationship, where a record in one entity can be referenced by multiple records in another entity.

How to Generate a Physical Diagram from a Logical Diagram in Vertabelo

Have you finished preparing your logical data model in Vertabelo? Awesome! In this article, we'll show you how to generate the physical data model from the logical model in Vertabelo. It’s just a few clicks away. Ready? Let's dive into it. Quick Intro In this article, we'll deal with a slightly modified version of Microsoft's Northwind Database. We often use it in our LearnSQL courses, such as Customer Behavior Analysis in SQL.

What Is a One-to-Many Relationship in a Database? An Explanation with Examples

One-to-many relationships are one of the most common database relationships. If you want to learn when and how to use one-to-many relationships, then this article is a great starting point. You will surely use one-to-many relationships to store information in any relational database, whether you are designing enterprise-level software or just creating a simple database to keep track of your uncle’s stamp collection. A Brief Introduction to the Relational Model Relational databases are a core component of any modern transactional application.

What Is a Many-to-Many Relationship in a Database? An Explanation with Three Examples

What is a many-to-many relationship in database modeling? How do you implement this relationship in a database? The examples in this article will answer these questions. Many-to-many relationships are probably the trickiest relationships to show in a database. So, my first step in this article will be to explain what they are. Then I’ll move on to giving you several examples of many-to-many relationships, keeping them as close to real life as possible.

Common ER Diagram Mistakes

Get to know the ER (Entity Relationship) diagram, its parts, and what often goes wrong when creating it. Have you ever created a relational database model? Or maybe you're trying to create your first one? You know (or you'll soon find out) that translating real-world problems to database logic can sometimes be quite difficult. One of the tools that might help you is the ER diagram. Common database design wisdom holds that the better your ER diagram, the easier it will be to build the database model.

Integrated Transport Data Model

Integrated transport is something we often hear about on the internet or in the news. While it’s not something new, it’s definitely an ongoing process, with constant changes being implemented. Today, we’ll take a look at a data model that could handle zone, passenger, and ticket info. Let’s dig right into our integrated transport data model, starting with the idea behind it all. Idea Integrating transportation is necessary to maximize its efficiency and, for customers, its easy use.

Payroll Data Model

A payroll data model allows you to easily calculate your employees’ salary. How does this model work? No matter whether you’re running a small or large company, you need some kind of payroll solution. That’s where a payroll application comes in handy. Plus, the bigger the company, the harder it gets to handle the employees' salary calculations; here, a payroll application becomes a necessity. To help you understand all the data required for such an application, we’ll walk you through a related data model.

911/112: An Emergency Call Service Data Model

Calling an emergency number like 911 or 112 is not something we’re looking forward to, but we’re glad to have it when we need it! On the other end of the line, it’s a stressful job, and there’s little room for mistakes. Everything needs to work perfectly. Today, we’ll take a look at the data model an emergency service could use to process and respond to incoming calls.

Track Signals with a Signal Processing Data Model

Cameras, revolving doors, elevators, temperature sensors, alarms – all of these devices produce a large number of interconnected signals that are related to events happening around us. Now imagine you’re the person who needs to track statuses, produce real-time reports, and make predictions based on all this signal data. To do this, you’d first need to store that data. A data model that supports such signal processing is the topic of today’s article.

Using Python and MySQL in the ETL Process: Using Python and SQLAlchemy

In the previous two articles of this series, we discussed how to use Python and SQLAlchemy to perform the ETL process. Today we’ll do the same, but this time using Python and SQL Alchemy without SQL commands in textual format. This will enable us to use SQLAlchemy regardless of the database engine we’re connected to. So, let’s start. Today we’ll discuss how to perform the ETL process using Python and SQLAlchemy.

Using Python and MySQL in the ETL Process: SQLAlchemy

SQLAlchemy helps you work with databases in Python. In this post, we tell you everything you need to know to get started with this module. In the previous article, we talked about how to use Python in the ETL process. We focused on getting the job done by executing stored procedures and SQL queries. In this article and the next, we’ll use a different approach. Instead of writing SQL code, we’ll use the SQLAlchemy toolkit.

Using Python and MySQL in the ETL Process

Python is very popular these days. Since Python is a general-purpose programming language, it can also be used to perform the Extract, Transform, Load (ETL) process. Different ETL modules are available, but today we’ll stick with the combination of Python and MySQL. We’ll use Python to invoke stored procedures and prepare and execute SQL statements. We’ll use two similar-but-different approaches. First, we’ll invoke stored procedures that will do the whole job, and after that we’ll analyze how we could do the same process without stored procedures by using MySQL code in Python.

Designing a Database for a Recruitment System

Do you want to learn how to design a database system and map a business process to a data model? Then this post is for you. In this article, you’ll see how to design a simple database schema for a recruitment company. After reading this tutorial, you will be able to understand how database schemas are designed for real-world applications. The Recruitment System Business Process Before designing any database or data model, it is imperative to understand the basic business process for that system.

The Important Dates Data Model

Are you forgetting something? A data model to help you remember important dates – before they happen. Have you ever forgotten an important date – your mom’s birthday or your anniversary? Or that you’re giving a lecture? Yup, things like that happen in real life. Maybe not to all of us, but to some of us (including me), they certainly do. To prevent such disasters, we’ll create a data model you could use as the background for an application that will notify you right on time.

Automobile Repair Shop Data Model

Running an automobile/car repair shop is a really complex business. You’ll need to make appointments while some customers will drive in and you don’t want to have them wait for hours. Also, you’ll need to organize employees, track repairs, materials, charge customers, etc. You’ll definitely need an IT solution and, of course, a data model in the background. Today we’ll talk about one such model. The Idea I’ve already mentioned that this business model is really complex.

The Smart Home Data Model

Smart homes used to be strictly in the future; now they are a reality. Most of us have heard about them, but they are not so widespread as they will be in the near future. Managing your home the ‘smart’ way will definitely produce a lot of data. Today, we’ll analyze a data model we could use to store smart home data. The Data Model When you think of a smart home, you probably think of remotely locking and unlocking your home, activating alarms, lights, or cameras from your phone, having thermometers that automatically manage your heating and cooling, etc.

The 9 Most Common Database Design Errors

You’ve probably made some of these mistakes when you were starting your database design career. Maybe you’re still making them, or you’ll make some in the future. We can’t go back in time and help you undo your errors, but we can save you from some future (or present) headaches. Reading this article might save you many hours spent fixing design and code problems, so let’s dive in. I’ve split the list of errors into two main groups: those that are non-technical in nature and those that are strictly technical.

Facts about Facts: Organizing Fact Tables in Data Warehouse Systems

The process of defining your data warehousing system (DWH) has started. You’ve outlined the relevant dimension tables, which tie to the business requirements. These tables define what we weigh, observe and scale. Now we need to define how we measure. Fact tables are where we store these measurements. They hold business data that can be aggregated across dimension combinations. But the fact is that fact tables are not so easily described – they have flavors of their own.

Beverly Hills 90210 and ZIP+4: Handling Addresses in Data Models

.address { max-width: 70%; padding: 20px 20px 10px 30px; margin: 40px auto; background-color: #ebebeb; color: #5b9bd5; border: 0px solid #360063; border-radius: 8px; -webkit-border-radius: 8px; -moz-border-radius: 8px; -khtml-border-radius: 8px; text-align: center; } In my last post, I wrote about ensuring that your data model properly handles global information: numbers, currencies, phone numbers, addresses, dates, and time zones, among other things. However, I’ve realized that many example data models have exactly the “self-centric” or “Amero-centric” approach that I cautioned against.