Top 7 Courses to learn PostgreSQL Database in 2025 - Best of Lot

PostgreSQL is one of the most popular databases after the big three - Oracle, SQL Server, and MySQL. PostgreSQL is commonly known as Postgres and is often referred to as the world's most advanced open source database. If you are looking to learn PostgreSQL in 2025 and looking for some useful resources like books, tutorials, and courses then you have come to the right place. In this article, I am going to share some of the best PostgreSQL online courses for beginners. These courses will cover topics ranging from installations to writing basic queries and retrieving data from tables. you will also explore the logic of SQL Joins, and a few best practices which are essential while working in a real-world, production PostgreSQL database.

Grokking the SQL Interview is Available Now !!

Hello guys, I am feeling proud and excited to announce the release of my new book, "Grokking the SQL Interview", a book, which programmers, Data Scientist, Data Analyst, QA, Business Analyst, and Junior DBAs can use to prepare for SQL question on tech interviews. Yes, it's finally available now after 2 years of waiting and you can purchase it now on Gumroad for a special price of just $10.95 (original price $21.90). I thought about this book 4 years ago , and it took really long to work on this as I tried to make it as perfect as possible.

Top 5 Jose Portilla Courses from Udemy to Learn Python, SQL, and Data Science in 2025 - Best of Lot

Hello guys, If you have joined any course on Udemy then I am sure you will have your favorite instructor, I have many and in the past I have shared best Udemy course by Maximillian Schwarzmuller and today, I am going to share best Udemy courses by Jose Portilla, anothe of my favorite instructor when it comes to learn Python, Data Science, and related technologies. Jose Portilla is unquestionably one of Udemy's most popular Data Science and Machine Learning professors. His courses are a treasure for data junkies, with over 3,500,000 total students and an average rating of 4.5+/5 stars from 800,000+ evaluations. 

Top 10 Tools Data Scientists and Machine Learning Developer Should Learn in 2025

Hello guys, if you are learning Data Science and Machine Learning in 2025 and looking for essential tools and libraries then you have come to the right place. Tools are very important for professional developers as they help them to do their job more efficiently. There is also a saying that a craftsman is as good as their tools and this is even more important in the field of Data Science and Machine learning as you have to deal with large datasets. You often need powerful tolls to normalize data, clean data, visualize data as well as build and test models. In the past, I have shared essential tools for Software developers,  tools for Java developers, essential tools for Python developers, as well as important tools for Web Developers, and today I am going to share essential tools for Data Scientists and Machine Learning developers, and engineers.

How to add Primary key into a New or Existing Table in SQL Server? Example

Since a primary key is nothing but a constraint, you can use the ALTER clause of SQL to add a primary key into the existing table. Though it's an SQL and database best practice to always have a primary key in a table, you will often find tables that don't have a primary key. Sometimes, this is due to lack of a column that is both NOT NULL and UNIQUE (constraint require to be a primary key), but other times purely due to lack of knowledge or lack of energy. If you don't have a column that can serve as the primary key, you can use identity columns for that purpose. Alternatively, you can also combine multiple columns to create composite primary keys, like you can combine firstname and lastname to create a primary key name, etc.

How to increase length of existing VARCHAR column in SQL Server? Example Tutorial

You can increase the length of a VARCHAR column without losing existing data in SQL Server. All you need to do is execute the following ALTER TABLE statements. Though, you need to specify NULL or NOT NULL constraint explicitly, depending upon your data.

Here is the SQL command you can use to increase the length of a VARCHAR column in SQL Server:

ALTER TABLE Books ALTER COLUMN title VARCHAR (432)

This command increases the length of the title column of the Books table to 432 characters. You can use the same command to increase the length of CHAR, NCHAR, or NVARCHAR columns as well.

Top 5 Courses to Learn Microsoft SQL Server Database and Transact-SQL in 2025 - Best of Lot

Hello guys, you might know that along with Oracle and MySQL, Microsoft SQL Server is one of the most popular relational databases in the tech world. It's used in many big organizations like Investment Banks, Insurance companies, and particularly at firms that use Microsoft technologies like Windows Server. With the growing popularity and market share of Microsoft Azure, there is a good chance that the demand for Microsoft SQL Server will also increase, particularly in the cloud. There is already a high demand for both Microsoft SQL Server DBA and Programmers who have SQL Server experience, and that's why it's an excellent decision to learn MSSQL in 2025.

Top 5 Free Udemy Courses to learn Oracle Database and SQL Online in 2025 - Best of Lot

Hello guys, if you want to learn Oracle SQL and look for free online courses, you have come to the right place. Earlier, I shared the best SQL and Database courses and books, and today, I will share free Oracle SQL courses for beginners. These are free courses from Udemy, Pluralsight, Coursera, and other reputed online learning websites. They are made accessible for education and learning purposes.  Thousands of people have already joined this course, and you can also do the same and learn Oracle SQL from the comfort of your home or office. 

Top 6 Advanced SQL Books for Experienced Programmers in 2025 - Best of Lot, Must read

If you an experienced programmer and know how to write SQL queries and database fundamentals but want to take your SQL and database skills to the next level then you have a come to the right place. In this blog, I have shared a lot of free SQL books and courses you can use to start your SQL journey. This is also the second article about SQL books, In the first part, I have shared some of the best SQL books which are essential to learning SQL queries and fundamentals of database like normalization, indexing, and other design stuff, if you haven't read it yet, I suggest to do it now. You will find some amazing books to start learning SQL.

Top 4 Books to learn Oracle PL/SQL Programming in 2025 - Best, Must Read

In last summer, I had to work on a Java project which was using the Oracle database at their backend. The project was a mix of Java code with Oracle PL/SQL stored procedures, where Stored procedures were quite big and complex to read. I had not worked on Oracle for a couple of years and almost forget whatever I knew before. So, to revise, update and re-learn and I looked over some of the books and online courses like The Complete Oracle SQL Certification Course which helped me a lot. In my quest to revise and re-learn Oracle SQL, I also find lots of their used books on Oracle PL/SQL which are both interesting to read as well as provides a great wealth of information to any programmer.

Top 6 Free SQL Courses for Beginners to Learn Online in 2025 - Best of Lot

Hello guys, we are already in the second week of New year, and everyone is talking about their goals to improve them as a better person, a better programmer, or better health. If you have also made your goal, and one of them is to improve your SQL skill, you have come to the right place because I will share some of the free online courses to learn and master SQL this year. The list includes a free course from Udemy, a popular online portal to learn Oracle, PostgreSQL, and Microsoft SQL Server. Yes, I have tried hard to include free courses on different databases to choose the course you want. 

Top 5 Udemy Courses to Learn MySQL in 2025 - Best Of Lost

Hello guys, if you are interested in learning SQL with MySQL database and looking for some awesome resources e.g. books, tutorials, and online courses then you have come to the right place. In past, I have shared some useful books and tutorials and in this article, I am going to talk about some of the best MySQL online courses from Udemy, Coursera, and Pluralsight which you can join to learn SQL and MySQL from the comfort of your office or home. In the last couple of years, you might have heard the statement that everybody should learn to code, which is great. Coding is now like reading, writing, and speaking skills and in today's Information technology-centric world it is a must-have and there is no better way to start coding than learning SQL, the most popular programming language.

Top 10 Courses to Learn SQL and Database in 2025 - Best of Lot

Hello guys, if you are a computer science graduate or new to the programming world, interested in learning SQL, and looking for some excellent resources, like books, courses, and tutorials to start with, then you have come to the right place. In the past, I have shared some of the best SQL books and tutorials, and today I am going to share some of the best SQL and database courses to learn and master this useful technology. If you don't know what SQL is and why you should learn it, let me give you a brief overview of SQL for everyone's benefit. SQL is a programming language to work with a database. You can use SQL to create database objects, like tables, stored procedures, etc., and also to store and retrieve data from the database.

The multi-part identifier XXX could not be bound in SQL SERVER [Solution]

Problem, I was doing join statement and getting this error Msg 4104, Level 16, State 1, Line 69

The multi-part identifier "a.X" could not be bound."

Cause:

I was mixing implicit joins with explicit joins. That is allowed, but you need to be aware of how to do that properly.

The thing is, explicit joins (the ones that are implemented using the JOIN keyword) take precedence over implicit ones (the 'comma' joins, where the join condition is specified in the WHERE clause).

Top 5 Websites to Learn SQL Online for FREE - Best of Lot

SQL is one of the most important skills for any programmer be it a Java, C++, Python, JavaScript, or Ruby developer. Almost 95% of the Java applications use a relational database in their back-end and almost all web applications use the database. In recent years, one of the most common ways to learn any programming skill is online, at your comfort of the office or home and SQL is no different. Learning SQL online has another advantage of a quick head start because you don't need to install a database and create tables to write some SELECT queries. 

How to replace NULL with Empty String in SQL Server? ISNULL() vs COALESCE() Examples

We often need to replace NULL values with empty String or blank in SQL e.g. while concatenating String. In SQL Server, when you concatenate a NULL String with another non-null String the result is NULL, which means you lose the information you already have. To prevent this, you can replace NULL with empty String while concatenating. There are two ways to replace NULL with blank values in SQL Server, function ISNULL(), and COALESCE(). Both functions replace the value you provide when the argument is NULL like ISNULL(column, '') will return empty String if the column value is NULL.

Difference between char, varchar, nchar and nvarchar data types in SQL Server? Example

What is the difference between char and varchar in SQL, followed by nchar and nvarchar, is one of the popular SQL interview questions, and surprisingly not every programmer knows this basic difference. If you go with the name, which you should, then you can figure out that char is a fixed-length data type while varchar should be a variable-length data type. Though all char, varchar, nchar, and nvarchar are used to store text or String data there are subtle differences between them. As I said char is fixed length, which means a variable or a column like Zipcode char(10) will take only 10 bytes to store data, including space.

Top 5 Books to Learn SQL and Database Design for Programmers and DBAs - Best of Lot

The database design and modeling are one of those topics which rarely get the attention they deserve, especially at the start of the project, but once things have gone out of hand, then everybody talks about them. Comments like - this database is designed poorly, the schema is not performing well, you cannot add a new column easily, etc. becomes very common. The most problem with database design is that it is mainly done by application developers like Java or C++ developer who knows SQL, but they are not the expert on how to design tables and schema. 

How to Find Duplicate values in a Table? SQL GROUP BY and Having Example| Leetcode Solution

Hello guys, if you are wondering how to find duplicate values in a table then don't worry, there are many ways to find duplicate rows or values from a given table. For example, you can use the GROUP BY and HAVING clause in SQL with count function to find all the rows which has same values for a particular column and then filter out rows where count is just one, I mean unique values. This way you can find all the duplicate from a given table. Using group by you can create groups and if your group has more than 1 element it means it's kind of duplicate.

How to use EXISTS and NOT Exists in SQL? Example Query and Tutorial

Hello Guys, you might have heard about how useful the EXISTS clause is helpful in writing sophisticated queries. Still, at the same time, I have also seen that many programmers struggle to understand and use EXISTS and NOT EXISTS clauses while writing SQL queries.  If you are one of them, then you have come to the right place. Today you will learn how to use the EXISTS clause in SQL by picking up a real-world example and an excellent SQL exercise from the LeetCode. Suppose that a website contains two tables, the Customers table, and the Orders table. Can you write an SQL query to find all customers who have never ordered anything?