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A Beginner’s Guide to SQL

by | Jun 10, 2022 | Blogs | 0 comments

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For anyone looking to break into the tech industry, SQL should certainly be ranked high up on your list of skills to learn. SQL originated back in the 1970s and to this day, it is still widely used in different industries, which renders this skill desirable and valuable to employers as there are high demands for it. 

According to Stack Overflow’s 2021 Developer Survey, SQL was ranked the third and fourth most popular language by professional developers and all respondents respectively, signifying the importance of possessing SQL as a skill trait.

Data in Today’s World

Data exists everywhere around us today. Take our mobile phones as an example. Our mobile phones consist of many apps, ranging from social platforms to games. Various types of data are being generated, namely, your Whatsapp and Telegram messages, photos and videos uploaded to Facebook and Instagram and much more. There are approximately 2.5 quintillion bytes of data being produced daily.

Where do all these chunks of data go exactly? This is where databases come in handy, functioning as a system and place which enables data to be stored, organised and managed conveniently. 

What is SQL?

SQL is an acronym for Structured Query Language, a language curated to manage databases. It has several usages, from creating data, to operating and retrieving them. It is also used in Relational Database Systems where it is considered a standard language. Examples of Relational Database Systems include Oracle, MySQL, MS Access and more. 

In these databases, data is structured and categorised in a table format, similar to the nature of an Excel spreadsheet which consists of rows and columns. Each row in a table is known as a record, while each column is known as a field. To illustrate, a retail company could possibly have a database with multiple tables, which include different categories like customers, employees and departments. 

Types of SQL statements

  • Data Definition Language (DDL)

SQL is used as a DDL, which refers to the process of creating and structuring a database, using it and deleting it.

  • Data Manipulation Language (DML)

Additionally, SQL is used as a DML, which is to maintain a database that already exists. This process involves the entry, modification and extraction of data.

  • Data Control Language (DCL)

It is also utilised as a DCL, where users can protect their database against corruption and misuse.

  • Data Query Language (DQL)

Commands, such as SELECT are called DQL, which is used to fetch data from the database. The purpose is to get schema relation based on the query passed to it.

  • Transaction Control Language (TCL)

TCL is used to manage information or transactions in a database.


CRUD, abbreviated for create, read, update and delete is an essential operation which involves the basic SQL queries. It is applicable to almost every database and database design.

  1. Create

The Create operation allows you to create new records in the table. In certain SQL relational database applications, the command for the Create operation is INSERT.

  1. Read

Read enables you to retrieve the contents of your selected table. The SELECT command is used for the Read operation.

  1. Update

The Update operation is used to alter the content of the table. For the Update operation, two commands are used, ALTER and UPDATE.

  1. Delete

Delete operation allows you to delete records from the table. The command is DELETE.

Data Types in SQL

There are plenty of data types used in SQL. The table below shows a clear overview of the different data types.

Data Types in SQL - SQL course Singapore

Real-life Applications of SQL

SQL and databases are universal and widely utilised in almost every industry generating large volumes of data. Being adept in it is essential for any data analyst as you would need to manage and retrieve data from the database in order to use Data Analytics tools and generate insights. 

Next, we will be illustrating certain real-life applications.

The healthcare industry requires huge databases due to the amount of data it produces on a daily basis. The database contains a plethora of information revolving around the healthcare staff, which consists of doctors, nurses, surgeons and many more. For instance, some of these information are personal particulars (name, address, contact numbers and department). Additionally, the database also contains information about the patients (personal particulars, history of appointments, prescriptions, blood tests, diagnoses and more). 

By having a database in place, whenever a patient goes for their appointment at the clinic or the hospital, authorised personnel like the doctors can easily retrieve the patient’s information from the database, and analyse the patient’s history of appointments, existing conditions and allergies to assess their current conditions and prescribe the appropriate medicine. 

Another illustration would be social networking sites. Social platforms like TikTok and Facebook use SQL for various purposes. These include retaining existing account details such as users’ profile details, keeping chat history between users which enables them to retrieve the messages and read it in their spare time and updating the database when new content is being published.

Our last example would be streaming services like Netflix and Disney+. The databases allow these apps to store a vast number of movies and TV shows that are of different genres. These data are then used to identify customer behaviour, namely trending shows, their favourite genres and more. SQL is also used to store user information such as transactions and billing information. 
These examples depict just how versatile SQL is. Did you know that SQL can work in a Python environment as well? Python libraries such as SQLite or MySQL were developed for this purpose.

Ways to Learn SQL

After learning and understanding the brief guide to SQL, one should recognise the importance of SQL and why it remains prevalent and popular amongst employers. 

If you are interested in becoming proficient in SQL, there are plenty of SQL programming courses being provided by organisations like Vertical Institute. Beginners are warmly welcomed since no prior knowledge is required at all, as these courses will build your basics and foundation of SQL. 

Embark on your journey of learning SQL by signing up for our Data Analytics course in Singapore today! Not only will you get to learn SQL but also other in-demand softwares like Excel and Tableau. 

About Vertical Institute

Vertical Institute prepares individuals for the jobs of tomorrow. We specialise in teaching in-demand skills, building the next generation of changemakers and inventors through our world-class tech courses and certifications. 

Singaporeans and PRs can receive up to 90% IBF Subsidy off their course fees with Vertical Institute. The remaining fees can be claimable with SkillsFuture Credits or NTUC UTAP.

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