27 Jan 2022 Kateryna Koidan How Do You Get Rid of Duplicates in an SQL JOIN? Do you have unwanted duplicates from your SQL JOIN query? In this article, I’ll discuss the possible reasons for getting duplicates after joining tables in SQL and show how to fix a query depending on the reason behind the duplicates. Data analysts with little experience in SQL JOINs often encounter unwanted duplicates in the result set. It’s challenging for beginners to identify the reason behind these duplicates in JOINs. Read more 7 Dec 2021 Kateryna Koidan Will SQL Ever Be Replaced? Is it worth learning SQL? Is it possible that one of the modern programming languages or no-code solutions will replace SQL very soon? No; it is not that easy to replace SQL and relational databases. Let’s see why SQL is future proof – and why learning it will pay off for many years to come. If you are building your career in a data-driven company, you are probably looking into opportunities to enhance your skill set in data management and data analysis. Read more 25 Nov 2021 Kateryna Koidan 5 Best Practices for Writing SQL JOINs These best practices for SQL JOINs will help you make readable SQL queries that deliver accurate, clear, and understandable output. Considering that relational databases are built around related tables, it’s no wonder that SQL JOINs – which allow you to combine information from multiple tables – are one of the primary skills acquired by SQL newbies. SQL JOINs course by LearnSQL.com is the perfect place to refresh your knowledge about JOINs. Read more 18 Nov 2021 Kateryna Koidan 5 SQL Subquery Examples SQL subqueries are basic tools if you want to communicate effectively with relational databases. In this article, I provide five subquery examples demonstrating how to use scalar, multirow, and correlated subqueries in the WHERE, FROM/JOIN, and SELECT clauses. A subquery, or nested query, is a query placed within another SQL query. When requesting information from a database, you may find it necessary to include a subquery into the SELECT, FROM , JOIN, or WHERE clause. Read more 27 Oct 2021 Kateryna Koidan SQL Date and Time Functions in 5 Popular SQL Dialects Are you confused by all the date and time functions used across different SQL dialects? In this article, I summarize the date and time data types used in PostgreSQL, Oracle, SQLite, MySQL, and T-SQL. I also provide examples with the key SQL date and time functions used across these dialects. It’s time to become date and time gurus! Do you want to calculate how often employees are running late for work? Read more 15 Oct 2021 Kateryna Koidan How to Join Only the First Row in SQL In your projects, you may encounter situations when you only need to join the first row with the most recent order to the corresponding record in another table. In this article, I’ll go through several ways to do this in SQL. The best way to practice basic and advanced SQL is our interactive SQL Practice track. It contains 10 SQL practice courses with onver 1000 hands-on exercises to help you refresh your SQL skills. Read more 14 Oct 2021 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. Read more 24 Sep 2021 Kateryna Koidan 7 Things Every Data Engineer Should Know People generate massive amounts of data every day. To get insights from data, organizations need to capture and process them efficiently. That is when data engineers are called up. In this article, I’ll discuss the data engineering role and the skill set necessary to succeed in the role. As the world generates more and more data every year, the IT industry creates new roles to deal with it. These roles include data analysts, data scientists, machine learning engineers, and data engineers. Read more 21 Sep 2021 Kateryna Koidan 5 Practical Examples of Using ROWS BETWEEN in SQL SQL window functions are tremendously useful for calculating complex aggregations like moving averages or running totals. The ROWS clause allows you to specify rows for your calculations, enabling even more sophisticated window frames. Here are five practical examples of leveraging the ROWS BETWEEN clause in SQL. Window functions (also called OVER functions) compute their result based on a sliding window frame (i.e. a set of rows). They are similar to aggregate functions in that you can calculate the average, total, or minimum/maximum value across a group of rows. Read more 16 Sep 2021 Kateryna Koidan How Developers Can Build SQL Skills Even though you cannot build an application using SQL, employers continue to add SQL skills to their job requirements for software developers. In this article, I’ll elaborate on why developers need to know SQL and how you can learn SQL most efficiently. As a developer, you may work on different kinds of projects. Not all of your projects require doing string manipulation, but that doesn’t mean you don’t need to know how to do this. Read more «« « 1 2 3 … 5 » »»