Data Analysis

Michał Wasiluk

An Introduction to Spatial Databases and Geospatial Data

Discover how spatial databases and geospatial data enhance spatial queries, support GIS integrations, and enable advanced data analysis. Spatial databases are specialized database systems designed to store, manage, and query geospatial data efficiently. These databases provide support for spatial data types and spatial indexing, allowing for complex spatial queries and analysis. Geospatial data, stored within these databases, represents information about the physical world tied to specific locations on Earth.

Jakub Romanowski

How to Find SQL Databases for Practice

Learning SQL is important for anyone working with data, but finding a SQL database for practice can be a challenge. In this guide, you'll find easy SQL queries (and some rather more complex) to help you get started using the databases from our new SQL Databases for Practice course. SQL can be fun and practical when you get to try out real queries on a real database. If you are a beginner this guide will help you get started with some simple SQL queries using the databases from our SQL Databases for Practice course.

Alexandre Bruffa

Integrating SQL with Looker for Data Analysis

You may have heard the term “data-driven”. All big companies nowadays have a data-driven approach; it simply means they make strategic decisions based on data analysis and interpretation. To streamline the process and stay competitive, companies rely heavily on data analysis and Business Intelligence (BI) tools. One of the most famous powerful BI platforms is Looker. Now owned by Google, Looker is well known for its data exploration, visualization, and reporting capabilities.

Kamila Ostrowska

What Is CRUD?

What is CRUD? In this article, we’ll explore the meaning of this acronym and its significance in the world of SQL and data analysis. CRUD is an acronym that stands for Create, Read, Update, and Delete. These are the four basic operations that can be performed on data stored in a database or other data storage systems. CRUD operations are fundamental to data management and are commonly implemented in database management systems (DBMSs), web applications, and Application Programming Interfaces (APIs).

Alexandre Bruffa

Types of Databases Explained

As an IT student or specialist, you can be sure that databases will be a key element of your professional life. So, you’ll need to understand the many types of databases available – what they do, when to use them, and how they’re different. That’s what we’ll cover in this article. Social media, online banking, e-commerce, AI assistants, and even your mobile phone could not exist without a database! Databases are essential for keeping data accessible and secure in any modern digital product.

Tihomir Babic

SQL Project for Portfolio: Northwind Store

SQL portfolio projects are an important part of a data analyst’s education. How do you start a project, and where do you go with the insights you discover? We’ll use the Northwind store database to answer this. Doing a solid SQL project is an essential element of any data analyst’s learning process. An SQL project is a great tool for learning, as it makes you use SQL on a real-world dataset.

Jakub Romanowski

New Course! Have Fun With Self-Guided Practice Databases

If you're looking for a place to experiment with your SQL queries and see them in action, our new "SQL Databases for Practice" course is the perfect spot. Dive in and play around with real data, right where the action happens! We're thrilled to launch a brand-new resource on LearnSQL.com, called SQL Databases for Practice. This course is all about giving you the freedom to sharpen your SQL skills on your terms, using real databases from various industries like education, e-commerce, and more.

Kamila Ostrowska

Mastering MySQL for Data Analysis

Mastering MySQL can significantly benefit anyone looking to advance in data science or database management. If you develop your data analysis skills in MySQL, you’re on the right path to positively influence your career. In this article, you’ll learn how to practice MySQL effectively and what kind of learning sources to choose. You’ll see for yourself that MySQL is not rocket science and that using it can be easy and intuitive.

Radu Gheorghiu

Integrating External Data Sources with SQL Databases

In today's world, data is the new currency and organizations are swimming in vast oceans of information from various sources. Trying to make sense of all this disparate data is a challenge; one of the most common ways to solve that challenge is by integrating external data sources with SQL. In this article, I'll guide you through strategies and techniques for seamlessly blending data from APIs, flat files, NoSQL databases, and other external sources into your SQL databases.

Nicole Darnley

Data Visualization Using SQL: A Complete Guide for Data Analysts

Start exploring data visualization using SQL with our practical guide. You’ll learn how to harness the powerful features of SQL to create effective visualizations that enhance your data analysis – and make it more understandable and impactful. SQL is a specialized programming language designed for managing and manipulating relational databases. It provides a standardized framework for querying, updating, and manipulating data. It is simple and yet offers a robust set of commands and functions to interact with data.

Maria Durkin

The Data Analysis Lifecycle: From Dataset to Presentation

In today's fast-paced decision-making climate, data is an invaluable resource. Raw data is like a rough diamond: it has great potential, but it must be processed to reveal its true brilliance. Achieving this brilliance is where the data analysis lifecycle comes in. The data analysis lifecycle maps out a structured journey of five steps: Collection Cleaning Analysis Interpretation Presentation Mastering the right tools for each step is key, and that's where SQL proves indispensable.

LearnSQL.com Team

Does Data Analytics Require Coding

Thinking about a future in data analytics? You might be pondering the need for coding skills. Is it necessary to be good at programming? As the worlds of data analytics, technology, and data science merge, the importance of coding becomes clearer. It’s crucial to understand which programming languages are key and how much expertise you need, making the journey into this vibrant field less daunting. In this article, we're going to focus on the importance of coding, particularly SQL, for data analytics.

Nicole Darnley

Efficient Data Analysis: Leveraging SQL with R

This article delves into the nuances of using SQL with R in data analysis. It offers insights and practical examples that demonstrate the effectiveness of this combination. By integrating SQL with R, analysts can leverage the strengths of both languages. This helps them perform comprehensive data analyses, going from initial data retrieval to complex statistical modeling and visualization. To kickstart our exploration of the dynamic duo of SQL and R in data analysis, it's essential to grasp how these two powerful tools can revolutionize the way we handle, manipulate, and interpret vast datasets.

Jill Thornhill

Integrating SQL with Python for Data Analysis

Integrating SQL with Python isn’t difficult. The two tools work together to combine the information-processing power of relational databases with the flexibility of a programming language. In this article, I will discuss the benefits of data analysis using SQL and Python, with real-world coding examples. Why do most of the best data analysis tools on the market – such as Tableau and Power BI – include both SQL and Python in their toolboxes?

Alexandre Bruffa

Using SQL in Data Warehousing

SQL is a key player in organizing and analyzing data in data warehouses. In this article, I'll introduce you to the basics of SQL in data warehousing. We’ll learn how this powerful language helps manage large datasets, making your work easier and more productive. Whether you're a student diving into the world of technology or an experienced specialist navigating the domain of data, understanding the concept of data warehousing is fundamental.

Jakub Romanowski

Analyzing Social Media Data with SQL

Diving into the world of SQL social media analysis? This guide will help you start using SQL to analyze and interpret data from social media platforms. Get ready to transform your approach to digital data and unlock new possibilities in social media analytics! Welcome to the exciting world of SQL and social media analysis! If you're new to this field, you're about to discover how powerful a tool SQL can be in understanding the vast sea of data generated on social media platforms every day.

Maria Durkin

SQL and Power BI: Transforming Data into Insights

The need for powerful tools that enable efficient data analysis and visualization has never been greater. Enter SQL and Power BI, a potent duo that enables businesses to maximize the value of their data assets. First, let’s explain what SQL and Power BI are; then we’ll discuss how and why they make such a great pair. SQL, or Structured Query Language, allows you to communicate with databases, making it the foundation of data management.

Maria Durkin

SQL for Data Analysis: 15 Practical Exercises with Solutions

Are you new to the world of SQL and eager to unlock the power of data analysis?. In this article, we'll improve our SQL skills through 15 practical, hands-on exercises designed specifically for beginners. Because when it comes to SQL, practice truly makes perfect! We’re going to shine a spotlight on the critical domain of data analysis, where SQL takes center stage. SQL, or Structured Query Language, plays a pivotal role in data analysis.

Jakub Romanowski

How to Prepare for the SQL Assessment Test

In this guide, I’ll walk you through the essentials of SQL assessment preparation, from understanding database management to mastering data analysis and SQL commands. Let’s dive in and set you on the path to success. In today's data-centric world, mastering SQL proficiency holds paramount importance. Whether you're a seasoned database manager or a newbie exploring the realm of database management, gearing up for an SQL Assessment is crucial. Stepping into the world of SQL can be both thrilling and challenging.

Kamila Ostrowska

How SQL Can Help You Understand Your Clients Better

In this article, we will delve into how SQL can help businesses analyze customer data, uncover patterns, and make informed decisions to meet their clients' needs. Managing and understanding clients is crucial for any business, and this requires data. Client data, such as purchasing habits, preferences, and feedback, is typically stored in databases. To access and analyze this data, you need to be proficient in SQL, the language designed for managing and querying data in databases.

Alexandre Bruffa

Python vs. SQL for Data Analysis

You surely have heard about SQL and Python. Maybe you’ve even worked with one of those languages. Both have strengths and weaknesses. When it comes to data analysis, which should you use? This article will demonstrate how Python and SQL are useful for data analysis and how knowing both languages can boost your data analysis journey. Decided to get into data analytics? Great! An increasing number of companies are looking for people who can analyze data and draw conclusions from it.

Maria Durkin

How AI & SQL Can Accelerate Your Data Analysis Workflow

Did you know that using AI for data analysis can be a total game changer for SQL developers and data analysts? In this article, we’ll learn about how AI can help you level up your data analysis skills and why it’s a must-have tool in every data professional’s toolkit. Artificial Intelligence (AI) has emerged as a game-changer in the workforce, transforming industries and redefining how professionals deal with data. Specifically, the use of AI for data analysis is becoming increasingly critical in making informed decisions.

LearnSQL.com Team

SQL for Data Analysis Cheat Sheet

Welcome to our SQL for Data Analysis Cheat Sheet — a must-have resource for anyone looking to harness the power of SQL in the realm of data analysis. Whether you're a data enthusiast, a business analyst, or a seasoned data professional, this cheat sheet is designed to empower you to extract valuable insights from your datasets. Inside, you'll find a carefully curated collection of SQL commands and tips that will elevate your data analysis game.

Jakub Romanowski

Best SQL Books for Data Analysis

In the world of data analysis, SQL is a powerful tool. It's a language that helps professionals find, organize, and analyze the data stored in databases. If you're looking to learn this important skill, you've come to the right place. This article will guide you through the best SQL books for data analysis, whether you're just starting out or already have some experience. SQL (Structured Query Language) is a standard language used for working with databases.

Maria Durkin

SQL for Data Analysis: What Should I Learn?

You may already be aware of SQL's importance in data analytics. But what features of SQL are important to data analysis and where can you learn them? In this article, we will answer your questions. Before we talk about using SQL for data analysis, it helps to know what we’re talking about. So, let’s define these two things. Structured Query Language (SQL) is a programming language that is used to manage data in relational databases.

Jill Thornhill

Google BigQuery SQL Syntax: A Comprehensive Guide

What is Google BigQuery? What can it do for your organization? Is BigQuery SQL a valuable skill? Where can you learn it, and where can you get some practice? Very few organizations today are not computerized. Many processes now make use of the IoT (Internet of Things), where all kinds of devices are networked and continually feed real time data into computer systems. The result is a vast amount of data available for decision-making.

Nicole Darnley

Why Do You Need SQL to Work With Google BigQuery?

Data is just as important to your business as investing or accounting; that’s why many people use Google’s BigQuery data warehouse. In this article, we'll discuss why you should learn SQL if you want to start using BigQuery. Unleash the power of your data! In the ever-growing landscape of data-driven decisions, organizations are continuously on the lookout for tools that can help them handle and analyze their data efficiently. Enter Google BigQuery: a powerful, Cloud-based data warehouse designed to store and analyze massive datasets in record time.

Jill Thornhill

Why Is Data a Valuable Resource for Your Business?

How do you build an effective data resource and make it work for you? In this article, I'll look at why data is so important to any organization and how to make the most of your data resources. Bad decisions are almost always based on incorrect or incomplete facts. Good decisions keep your organization competitive. In a nutshell, that’s why data is such an important business resource. Ever since the dawn of civilization, our ancestors have known the value of information.

Maria Durkin

Why SQL Is the Perfect Database Language

Updated on: May 20, 2024 Which programming language should you learn if you want to work with databases? We’ll explain why SQL is the top choice! Learning a database language can be an incredibly valuable skill in today's data-driven world. But with so many options out there, it can be difficult to know where to start. In this article, we'll make a compelling case for why SQL is the ideal choice for anyone looking to dive into the world of databases.

Nicole Darnley

Top 7 Advanced SQL Queries for Data Analysis

Explore essential advanced SQL queries for data analysis. Structured Query Language, or SQL, is an indispensable tool for data analysts. Most people pick up the language relatively quickly and can begin in-depth data analysis after just a few lessons. Because of this, many data analysts tend to stay in the beginner/intermediate level of using SQL. This level of understanding allows you to “get the job done”, but it might not be the most efficient way to write a query.

Nicole Darnley

Data Cleaning in SQL

Data cleaning is an important part of any data analysis. Here we’ll discuss techniques you can use to do data cleaning in SQL. I find it nearly impossible to focus on work when my desk is a mess. If it’s cluttered with paper, coffee mugs, or random toys my daughter has somehow snuck into my office, there is no chance I will be able to get anything done until my desk is back in order.

Nicole Darnley

Learn SQL for Data Analysis with LearnSQL.com

Updated on: December 1, 2023 Discover how to learn SQL for data analysis and start making sense of your data today. Our guide provides a clear and simple SQL learning path for data analysts, helping you query databases and analyze data with ease. Whether you're starting from scratch or looking to polish your skills, we'll help you every step of the way. When I was in high school, I planned to go to college and major in interior design.

András Novoszáth

Why You Need Analytical Skills to Get Promoted at Work

Do you wonder if analytical skills might benefit you in your job? Are ‘analytical skills’ the same as data analytics? Is SQL a useful analytical skill? Read the article to answer these questions. Analytical skills allow you to better understand problems in your work; good analytical skills bring many benefits to your career. The term ‘analytical’ refers to a wide range of traits and capabilities, making it sometimes ironically vague and general.

Kateryna Koidan

Roadmap to Becoming a Data Analyst

What is a data analyst? What are their daily duties, and what skills do they need? In this article, I discuss the role of data analysts and share a step-by-step guide on how to become one. As organizations start to realize the value of their data on their customers, target audience, competitors, suppliers, and other market players, the role of data analysts becomes more important. To become a successful data analyst who can bring real value to the organization, you need to possess a specific set of skills.

Kateryna Koidan

Learn SQL for Data Science With LearnSQL.com

If you are interested in a data science career and have looked at a few relevant job descriptions, you've probably noticed many leading tech companies expect their data scientists to know SQL. Let's see how you can learn SQL for data science and become more valuable to any data-driven organization. A data scientist is a complex technical role that expects a combination of the skills of a statistician, a business analyst, and an IT expert.

Kateryna Koidan

How to Learn SQL for Marketing Analytics With LearnSQL.com

SQL is a valuable tool for any experts wanting to make data-driven decisions. Marketers are no exception. Let's explore how to design an effective learning path for SQL in marketing. SQL for marketing analytics is used to understand customers better and to increase the effectiveness of marketing campaigns. If you work in marketing and want to join other marketing experts who have already benefited from this tool, you need to learn SQL.

András Novoszáth

How to Get More from Your BI Tools with SQL

Are you frustrated with the limitations of your business analytics tool? Do you wonder if there are other features you could tap into? Would you like to know how SQL compliments your work with Power BI and Tableau? Read this article to learn more! If you are a data analyst or if data analysis is part of your everyday job, Business Intelligence (BI) tools are crucial for your work. You also know that most databases run SQL queries in the background of such tools.

Kateryna Koidan

Use SQL for Data Analysis With the New Google Analytics 4

As Google is sunsetting its Universal Analytics in favor of Google Analytics 4, data analysts need to adapt and learn how to get the most from the new tool. In this article, I'll discuss how to enhance your data analysis by using SQL with Google Analytics 4. Universal Analytics by Google has been helping data analysts and marketers in all industries everywhere understand their audience better. However, Google recently announced they would stop their support of Universal Analytics on July 1, 2023.

Himanshu Kathuria

These SQL Queries Will Help You With Data Analysis

Need to streamline your everyday data analysis tasks? This article explains how basic SQL queries can help. If you are planning a corporate career or any field that involves working with data, you must have come across SQL, or Structured Query Language. SQL was first developed in the 1970s and it continues to be the industry standard for database interactions. Many of you may already have decided to learn this language, given how powerful it is.

András Novoszáth

5 Tips for You From a Senior SQL Data Analyst

Are you looking for tips for becoming a better data analyst? Do you want to know about the mistakes and issues you may face? I have collected five tips for your everyday work based on my experience as a data analyst. You may have already read about what data analysts do, how much they earn, and how to become one. However, there is more to it than just becoming a data analyst.

Himanshu Kathuria

Why Should Every Data Analyst Know SQL?

Updated on: May 15, 2024 Want to become a data analyst? Then you’ll want to get cozy with SQL. In this article, I’m going to break down why mastering SQL is not just helpful but essential. We’ll look at how it can beef up your analysis skills and open doors to some really exciting job prospects. So, let’s see why SQL is a must-have tool for anyone aiming to be a top-notch data analyst.

Kateryna Koidan

Are You Ready to Become a Data Analyst?

Data analysts enjoy strong career prospects. Do you have the skills required for this role? Let’s find out! If you enjoy working with data, searching for interesting patterns and valuable insights, you may wonder “Should I become a data analyst?” In this article, I’ll explain what data analysts do and what skills a successful data analyst needs. What Does a Data Analyst Do? Data-driven organizations rely on specialists who know how to get value out of data.

Karolina Niewiarowska

Here’s How I Started Creating SQL Reports

Once upon a time, there was a girl who was just starting her adventure with learning SQL. As a marketer, one of her tasks was writing reports. Previously, she used Excel, a calculator, and written notes to prepare the reports her boss required. One day, it turned out that she could do her job much faster and easier. That was the day she read about SQL reports for the first time.

András Novoszáth

Here’s Why You Should Use SQL for Sales Analytics

Would you like to understand how your sales efforts play out so that you know where to put your focus? Do you want to empower your sales teams with sales analytics? This article shows you how you can use SQL to use your sales data to your advantage. If you work in sales, understanding the activities that produce results has financial consequences for you, your team, and your company. This is where sales analytics can really help you.

Kateryna Koidan

Still Using Excel for Data Analysis? See Why SQL Is Better!

Are you working with data and still using spreadsheets? Many people think that only programmers or professional data analysts can leverage SQL for data analysis. In this article, I’ll show how people with no IT background can use SQL for their daily work tasks. Not all people working with data have the corresponding job titles like data scientist, data analyst, or data engineer. Following the data democratization trend, almost all office workers do something with data as part of their daily duties – marketers analyze advertising campaigns, HR specialists analyze employee dynamics, auditors analyze credit portfolios, etc.

András Novoszáth

Read These 5 Data Analysis Books to Jump-Start Your Career

Do you want to pivot into a data analyst role, but you are unsure where to start? Do you do analytics in your job and would like to learn more about the big picture of data? Are you looking for a great data analysis book to read? In this article, you will find our selection of the best books on data analysis! If you are a business professional thinking about picking up data analytics skills, you may be wondering how you should start.

Himanshu Kathuria

Top 10 Tools for Business Analytics

Business Analytics is one of today’s hottest career fields. However, success as a business analyst requires that you learn the right skills and software programs. Let’s see what tools you should know if you want to be a business analyst. With the world generating immense amounts of data – and having systems in place to capture and manipulate that data to fuel business growth – job opportunities for business analysts are only going to grow.

András Novoszáth

Why You Should Use SQL in Marketing Analytics

Have you been wondering how you could use SQL in your marketing data analysis work? Would you like to create SQL reports to guide your marketing decisions? In this article, you will learn how to use SQL for marketing through plenty of use cases. Are you a marketing professional wanting to better understand the results of your marketing efforts? Do you want better means to prove your point and demonstrate the value you create?

Marcin Koryszewski

How Much Do Data Analysts Earn in 2021?

How Much Do Data Analysts Earn in 2021? How much does a data analyst earn? We did some data analysis ourselves. Nothing fancy, but it will give you some extra motivation for learning SQL for your data analyst gig. Data, data everywhere! We live in the world of (big) data. Having data is just the first step. Knowing what to do with it, how to interpret it, and what insights it holds, is true greatness.

András Novoszáth

Why You Should Work in a Data-Driven Company

Does accessing and using data collected by your company feel painful? Have you heard about data-driven companies? Working in a data-driven company may give you the ownership and the opportunities to use your company’s data. Read our article to learn more! If you work in a company, chances are that you want to do data analysis to solve problems. However, this is often not easy. You face many obstacles, impeding access to the data you need.

András Novoszáth

How SQL Can Help You Democratize Data in Your Company

Are you drowning in an ocean of data but lack the staff to find the treasures in it? Do bottlenecks clog your data and reporting processes? Have you heard about data democratization and wondered what all the fuss is about? In this article, we answer your questions! If you are a part of an organization that works with data, limited access is one of your biggest bottlenecks. It impedes data-related processes and prevents you from generating insights about your business.

Kate Stolarek

Skills Every Data Analyst Should Have

Updated on: June 26, 2024 If you’re a specialist seeking new job opportunities or a student looking for career advice find out if a data analyst job is something worth considering. In today's article, I explain the essential data analyst skills needed for success in the field and the benefits that come from performing such a job. Choosing a career can be tough, and it's normal to feel unsure. If you're reading this, you're probably in that spot right now.

András Novoszáth

Data Analyst vs. Data Engineer: A Full Comparison

Updated on: June 17, 2024 Do you want to become a data analyst? Or maybe you dream about being a data engineer? Can't make up your mind? I'll help you. Read about the two roles’ history, their market situation, and the skills you need to become one in this data engineer vs data analyst comparison. You already know that it's a good idea to enter the data world and work with databases.

Himanshu Kathuria

Why Does Your Company Need Data Analysis?

Updated on: June 22, 2024 Data is the new gold. That is what the biggest in the business say, knowing the value of the data, the analyses, and the conclusions they bring. If you are wondering why your company needs data analysis and what value it could bring to your business, this article is for you. Many companies have used financial data analysis to boost revenue, cut costs, and increase profits.

Himanshu Kathuria

Analyze Small Datasets with SQL

If you think SQL data analysis is useful only when a business is generating millions of rows of data – that SQL cannot help you if you are generating a limited dataset – think again and read on! There is so much talk about how SQL is useful in analyzing Big Data that sometimes the applications of SQL data analysis for small datasets can go unnoticed. Having worked with early-stage businesses – which have just started generating data through daily transactions – as well as big established clients generating terabytes of data, I can tell you for sure that SQL can be an extremely handy tool for just about any business.

Tihomir Babic

6 Advanced SQL Queries for Analyzing Financial Data

Are you an advanced SQL user who’s new to finance? Do you want to learn how to use your knowledge to analyze financial data? The article will give you some guidance. You probably know that SQL is a potent tool for analyzing all sorts of data. The bigger and more complex data, the more beneficial SQL becomes. In certain situations, financial data can be very complicated; producing a sophisticated analysis requires sophisticated tools.

Shanika Wickramasinghe

Why Use SQL Over Excel

SQL is replacing Excel in many fields, and data analysis is certainly one of them. If you are still using Excel as a data analyst, you are missing something very valuable. SQL can make your life easier, as it's more efficient and faster than Excel. So, how and from where can you learn SQL? How Can SQL Help Data Analyst? You can use SQL to help you with the following work:

Aldo Zelen

SQL Indexing 101

Indexes are one of the most misused and misunderstood entities in physical database design. A good understanding of indexes and how they solve database performance problems is necessary for any database novice. In this article, we'll look at basic database indexes and their role in database development. To picture what an index is, consider a textbook. At the end of most textbooks is an index listing all the terms one can find in the text and the pages on which they appear.

Aldo Zelen

How to Use a SQL Wildcard

SQL wildcard allows us to filter data matching certain patterns in SQL. We use SQL wildcards with the LIKE operator in the WHERE clause of a query to filter data. In this beginner’s article, we’ll look at everything you need to know about basic SQL wildcards. If you like playing cards, then you know that wildcards can substitute any other card in your deck. Similarly, SQL wildcards can substitute one or more characters.

Dorota Wdzięczna

Our Picks for 2020’s 7 Best Online SQL Schools

If you’re looking for the best online SQL courses but aren’t sure where to start, you’re in the right place. I evaluated the top 7 ranked SQL schools available online to help you find the right solution. While summer is a great time to relax and get away from work, it’s also an excellent opportunity to learn new skills – like SQL! Thanks to SQL schools putting their courses on the internet, learning new tech skills is super easy and you can choose from a variety of formats to suit your needs.

Kate Stolarek

Why Learn SQL Over the Summer

Think summer is reserved for flying to warm places and hanging out at the beach? Sure! But it's also a great time to learn new skills that you haven't had time for. If you recently graduated from high school and want to get a head start on computer programming for college, learning SQL over the summer is a great opportunity. You have nothing to lose and everything to gain—SQL is actually really easy to learn, especially with so much free time over the summer.

Ignacio L. Bisso

Improving Slow Query Performance: When Runtime Matters

As SQL users, we usually focus on writing queries that return correct results. However, there are more things to consider when you're writing a query; one of them is query performance. In this article, we'll look at some examples where query response time is critical. Scene One: 911 Call Center Let's suppose we're at a 911 call center, when the phone rings. One of the operators answers the call; a witness reports that a man has been shot.

Ignacio L. Bisso

Converting Subqueries to Joins

Not all queries are alike, especially in terms of performance. In this article, we'll look at how you can convert SQL subqueries to joins for improved efficiency. When should I use SQL subqueries? Great question! Unfortunately, there's no concrete answer. SQL beginners tend to overuse subqueries. Typically, once they find that SQL construction works in one situation, they try to apply that same approach to other situations. It's only natural.

Ignacio L. Bisso

Learn to Write a SQL Correlated Subquery in 5 Minutes

If you’re familiar with the famous Russian nesting doll, then SQL correlated subqueries should be a peace of cake to understand—subqueries are just queries nested within queries. An SQL subquery is often called an “inner” query; the main query is usually called the “outer” query. This article covers everything you need to know about correlated subqueries. What Exactly is a SQL Correlated Subquery? A correlated SQL subquery is just a subquery that is executed many times—once for each record (row) returned by the outer (main) query.

Aldo Zelen

How to Become a Database Analyst

Curious about becoming a database analyst? Maybe you've taken some database courses at university and they really struck a chord. Or maybe you learned online. Now you're thinking about making a career out of working with databases. Where would you start? What should you expect at each phase of your professional development? In this post, we'll explore the challenging and exciting world of databases analysis. We'll go from the very beginning of a career to the apex of professional success.

Ignacio L. Bisso

Extracting Data From a String: SPLIT_PART in PostgreSQL

Learn how to use split_part in PostgreSQL to extract data from strings. Quite often, we’d like to extract parts of a string when working with text values. A common example is when we have a full name and need to retrieve only the last name. In this article, we’ll examine how to do it using split_part in PostgreSQL, i.e. a string-related function that can be used to extract a substring.

Dejan Sarka

Statistics in SQL: Dependencies Between Discrete Variables

In my previous article, we looked at how you can calculate linear dependencies between two continuous variables with covariance and correlation. Both methods use the means of the two variables in their calculations. However, mean values and other population moments make no sense for categorical (nominal) variables. For instance, if you denote "Clerical" as 1 and "Professional" as 2 for an occupation variable, what does the average of 1.5 signify?

Kacper Skawina

Analyzing Survey Data: Explore Results Using SQL

Excel is a powerful beast that lets you analyze complex data. Yet, operating on big chunks of data can sometimes be a daunting task. Let's take a look at how SQL can help. Today, we'll tackle a common problem with importing data to an SQL database, using a real-life example. Suppose your company conducted a survey on the most popular programming trends and preferences, striving to meet the expectations of its users.

Dorota Wdzięczna

SQL Hacks To Control Family Budget On Black Friday Weekend

If you’re in the US, chances are you’ve been eagerly awaiting the approach of Black Friday just as much as Thanksgiving. Though the shopping frenzy takes hold of nearly everyone, some people have to stick to their budgets and shop prudently. In this article, we’ll take a look at how generating an SQL report can help you track how much your family spent shopping on Black Friday. Storing Black Friday Purchases in a Database Before we can create an SQL report, we first need some data we can use.

Aldo Zelen

SQL Reporting Guide for Business Professionals

Working with the financial aspects of large and small enterprises can be a daunting task for a business professional. In this article, we'll look at several ways of constructing the perfect SQL report. You've probably already heard about SQL from your colleagues or in other areas of your career. If you're here, you've likely concluded that learning SQL will make your professional life easier – and you're right!

Dejan Sarka

Statistics in SQL: Calculating Frequencies & Histograms

Database and Business Intelligence (BI) developers create huge numbers of reports on a daily basis, and data analyses are an integral part of them. If you wonder whether you can perform statistical analysis in SQL, the answer is ‘yes’. Read my article to learn how to do this! Statistics are very useful as an initial stage of a more in-depth analysis, i.e. for data overview and data quality assessment. However, SQL statistical analysis possibilities are somewhat limited as there are not many statistical functions in SQL Server.