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  SQL is a powerful language for manipulating data in relational databases. However, when multiple users or applications access the same database concurrently, there is a risk of data inconsistency or corruption. To prevent this, SQL provides mechanisms for managing transactions and locking. In this blog post, you will learn what transactions and locking are, why they are important, and how to use them in SQL. This blog post is part of a series of SQL Learning guides that I am writing to help students and beginners learn SQL. If you want to join this SQL series learning community, follow to my  LinkedIn  and stay tuned for more updates. What is a Transaction? Image from  history-computer.com/ A transaction is a logical unit of work that consists of one or more SQL statements that are executed as a whole. A transaction has four properties, known as  ACID  →: Refer my blog ( Understanding ACID Properties ) Atomicity : A transaction either succeeds or fails as...

Null values are a common and tricky phenomenon in SQL databases. They represent the absence or unknown of any data in a column. In this blog post, we will learn how to handle null values in SQL queries using various techniques and functions. This is part of our SQL Learning series, where we cover the basics and advanced topics of SQL simply with examples. If you want to learn more about SQL, check out our other posts in the series and join our SQL learning community. What is Null in SQL? Image from Vlog Ankit Bansal Before we dive into the techniques of working with null values, let’s first understand what null means in SQL. Null is not a value, but a special marker that indicates that there is no data in a column. For example, if you have a table of customers, and some of them do not have a phone number, you can use null to represent the missing data in the phone column. Null is different from zero, blank, or empty string. Zero is a numeric value, blank is a string value with...

  Windows functions are a powerful feature of SQL that allow you to perform calculations or transformations on a set of rows that are related to the current row. They are also known as analytical functions or windowing functions. In this blog post, I will explain what windows functions are, how they work, and how you can use them to solve common data analysis problems. I will also show you some examples of windows functions using the Row_Number(), Rank(), Dense_Rank(), and NTILE() functions. This is part of my SQL Learning series, where I share my tips and tricks on how to master SQL. If you want to learn more, you can follow me on Medium and  LinkedIn , and check out my other posts on SQL topics. What are Windows Functions? Windows functions are a type of function that operate on a subset of rows, called a window, that are related to the current row. A window can be defined by using the OVER clause, which specifies how to partition and order the rows in the window. For exampl...