How to use WHERE and HAVING clause in SQL? Example Tutorial

Hello guys, if you want to learn about WHERE and HAVING clause in SQL then you have come to the right place. This blog shall be explaining how to use WHERE and HAVING clauses in SQL. but it won't be fine if we just jump to it. We need a good understanding of what SQL is and what it is used for. SQL stands for structured queried language, as it sounds it is a language or syntax that is used to query the database.

Difference between MySQL vs NoSQL (non relational DB) - Pros and Cons

Hello guys, if you are wondering whether to choose a NoSQL database like MongoDB, Cassandara, or MySQL for your application then you have come to the right place. In an earlier article, MySQL vs PostgreSQL I had shared the pros and cons of choosing MySQL over PostgreSQL for your application, and in this article, I am going to show the benefits and drawbacks of choosing MySQL over NoSQL or vice-versa. 

How to do Pagination in SQL Server? Query Example Tutorial

 What is pagination?

Pagination, often known as paging, is a method of breaking down huge amounts of material into smaller, distinct pages. Pagination is a popular feature of online applications, as evidenced by Google. The primary principle of pagination is that when we search for anything on Google, the results are displayed on a different page.

Transposing data in SQL - Example Tutorial

What is Transposition?

A transposition is when data is rotated from one row or column to another in order to modify the data layout and make observations from a different perspective. Row to the column, column to column, and bidirectional transposition are examples of basic transposition algorithms. Others, such as dynamic transposition, transposition with inter-row computations, and join-based transposition, are more complicated. All are prevalent in data analytics and so worthy of investigation.

SQL cross join Example and it's performance

Hello guys, in the past, I gave you a quick overview of SQL JOINS where we learned about different types of JOINS like right, left, inner, and outer join, and in this article, we'll learn about the SQL CROSS JOIN idea in this post, and we'll back up our knowledge with simple examples and illustrations. So, let's start with the basics.

Difference between DDL and DML commands in SQL with examples

What are SQL commands?

SQL commands are just that: commands. It's used to send and receive data from the database. It may also be used to carry out particular activities, functions, and data searches.

SQL can build tables, add data to tables, drop tables, change tables, and define permissions for users, among other things.

MySQL vs PostgreSQL? Pros and Cons

When establishing a new project, especially one on the Web, choosing a database management system is frequently an afterthought. Most frameworks include an object-relational mapping (ORM) tool that hides the differences across platforms and makes them all run at the same speed.

What is Virtual columns in MySQL and How to use it? Example Tutorial

 What is a Virtual Column and where is it used?

Virtual/generated columns are a new feature in MySQL 5.7. Because the data in this column is computed based on a specified expression or from other columns, it is called a generated column.

Virtual columns resemble regular table columns in appearance, but their values are generated rather than saved on a disc.

Virtual columns are one of MySQL 5.7's most useful features; they allow you to store a value in a new field that is derived from one or more other fields in the same table.

Top 5 Common Errors and Mistakes in SQL and How to Solve Them

After writing some SQL code, you're ready to query your database. You type in the code, and nothing happens. Instead, you're presented with an error notice.  Don't give up! SQL, like any other computer language, is prone to coding mistakes. We'll go through a few frequent mistakes individuals make while creating SQL in this tutorial.

How to use ROW_NUMBER() Function in SQL with nondeterministic order? Example Tutorial

The ROW NUMBER window function has a wide range of uses, much beyond the apparent ordering requirements. Most of the time, while computing row numbers, you need to do it in a specified order, which you provide in the function's window order clause. 

How to filter data in SQL? WHERE, LIKE, and BETWEEN Example

In SQL, you can filter data using the WHERE clause in your queries. The WHERE clause allows you to specify a condition that must be met for a row to be included in the result set. You can use basic conditional operator, logical operator to filter based upon any condition as well as LIKE operator filter based upon any pattern. You can also filter on rang using IN and BETWEEN clause whose examples we will see in this article. 

Difference between Primary and Foreign key in Database and SQL

Hello guys, if you are preparing for database or developer interview then questions form primary key is very common on interviews. One of such question is primary key vs foreign key which is asked ot me multiple times during early stage of my career. Now my experience has grown so I don't see this question quite often but the concept is still very important for any database admin or programmer to understand. 

The key difference between primary key and foreign key is that primary key on one table can be foreign key on other related table. 

For example, you have two tables Employee and Department, each have primary key emp_id and dept_id, now if you want to link or join these two table then you created a column called dept_id on employee table to indicate which department a particular employee work and now dept_id is a foreign key in Employee table. 

How to concatenate columns in SQL Server? Example Tutorial

Hello guys, welcome to my new blog SQLrevisited. I have long back created this blog to exclusively share SQL and Database articles but never get time to start it until today. This is the first article on this blog and in this post, you will learn how to contact multiple columns in an SQL server.  Like Java and many other programming languages and databases, you can use the + operator to concatenate multiple columns in SQL Server. You can join as many columns as you want with the + operator but you must remember that concatenating with NULL will produce NULL, which means you can lose the information from other columns if one of them is NULL.