Introduction

In this group of articles we are going to learn everything about Structured Query Language (SQL) in detail. The articles are bit different as we are not going to repeat everything which we can see in the traditional textbooks or other books, the articles here are going to be 100% practical oriented.

Instead we will provide you with SQL work tools which you will need in your work space. No useless concepts everything is straight to the point and very easy to understand. The topics included in the group of SQL articles are the topics which are used by Data analysts and Data managers in their daily work space. SQL allows this professionals to manipulate large sets of data.

The advantage of learning SQL is that, its syntax is intuitive and used to solve sophisticated tasks quickly.

Why SQL?

Imagine and put yourself in the shoes of the employee or manager who is handling huge amount of data. The professional can be working in various domains like Business Intelligence (BI), Data Science, Database administration or backend web development. This jobs are related to storing large amount of data. Before carrying out any analysis on data first you have to retrieve it. To achieve all this you need SQL.

SQL is known as Structured Query Language. Among different types of programming language SQL is a declarative (non-procedural) programming language. This means while coding you don’t have to focus on how task will be done, but need to focus on what task is to be done.

Using a procedural (imperative) language “HOW”. The examples are C, Java, etc. In this you explicitly need to define the solution of the task.
For example:

• Please, open the door.
• Go outside
• Take the bucket I forgot there.
• Bring it back to me.

On other hand, in declarative(non-procedural) language “WHAT” this would sound like Fetch the bucket, please. We don’t need to go the process step by step. The algorithm is made in and there is a optimizer which divided the steps into smaller tasks to achieve that task.

It is a programming language specially designed for working with databases. It is used to Create, manipulate and share the Data. Especially data from Relational Database management systems. The way the computer extract data from database is by writing Query.

Query is a piece of code intuiting computer to perform certain operations that can deliver the desired output. The entire process is called as the querying the database. SQL allows you to write queries that the computer can execute and then provide database insights in return.

The good thing about SQL is that it is intuitive and easy to learn language. But be careful it does not means using it is going to be a simple task. Sometimes the business problems involves the processing of large amounts of data. Despite it is relatively simple it has power to perform complex tasks.

Introduction to Databases

Databases plays a very important role in SQL. Writing SQL queries become easier if you understand databases well. Each row in database has certain value and each row makes a record. A record is each entry which exist in a table. A field is a column in a table containing specific information about every record in the table. When data are in the form of rows and columns it means you are dealing with stored tabular data. Relational algebra allows us to retrieve data efficiently.

The smallest unit that can contain a meaningful set of data is called entity. The rows represent the horizontal entity and columns represent the vertical entity. The table is itself an entity but it can also be called as database object.

Different types of Database languages