SQL : An introduction


Structured Query Language (SQL). When working with data, SQL is one of the most important languages to understand. We look at what SQL is, what it is used for, and what professions you might be able to get if you learn SQL. Data is all around you, from the prices of things at your local grocery to the personal information that social media captures as you explore. Our world is built on data, and SQL makes it much easier to navigate that data. In this post, we will look at what SQL is and what it can be used for, as well as how to learn SQL and various SQL jobs that you could get if you learn the language. SQL is something you’ll need to master if you want to work in the data sector.


What exactly is SQL?

Structured query language, or SQL for short, is a programming language that connects with databases, as we described in our piece about what different programming languages are used for. SQL (commonly pronounced sequel) is designed to store, retrieve, manage, and alter data within a database management system. IBM created SQL in the early 1970s, and it became commercially available in 1979. It is widely regarded as the industry-standard relational database management system (RDBMS). To get data from databases, it employs groups of keywords known as statements. Let’s have a look at some of the SQL statements that are accessible.


SQL statements

It would take substantially longer to find the data you require if you navigated a large database without SQL. You can pick data by table and column type using the SELECT query. Instead of spending a lot of time searching manually, you may rapidly pinpoint data sets that fulfill all of the conditions of your search.

  1. The INSERT statement lets you insert new data into the tables. You can choose numerous columns to input your data into, just like the SELECT query.
  2. The Erase command does exactly what it says it does: it allows you to delete existing records from a table. A DELETE query also allows you to define which rows should be deleted based on certain criteria.
  3. The CREATE DATABASE statement is used to create a new database within your database management system. Similarly, after the database has been formed, CREATE TABLE is used to create a new table.
  4. The Change statement is used to UPDATE one or more database records. You have the option of updating all rows at once or using a condition to selectively change a subset.


What exactly is a database?

Databases are all around us, with practically every corporation and industry requiring digital storage of information. A database is a structured collection of data that can be conveniently saved, categorized, retrieved, and searched. There are several database types, and which one you select will be determined by the sort of data you want to store. Let’s have a look at some of the most common database types:

  1. Relational databases are organized in rows and columns, store and deliver data in various tables, and allow you to identify and retrieve data in connection to one another. SQL is used by all relational databases. A relational database management system is exemplified by Microsoft SQL Server.
  2. NoSQL databases are any databases that do not use SQL as their primary language. These databases are better suited for people who do not require organized data. We’ll go through these databases in further detail later. NoSQL databases, such as CouchDB, are an example.
  3. Cloud databases are any databases that run in the cloud, and access to these databases is provided as a service. They are low-maintenance and versatile. An example of a cloud database is Oracle Autonomous Database.
  4. Time-series databases are databases that have been optimized for time-stamped data in order to provide more accurate insights. A time-series database is an example of Druid.


What is the purpose of SQL?

Now that you understand what SQL is, you may be asking what it is used for. It is, as previously stated, a programming language used to communicate with relational databases. But let’s dig a little deeper into that. SQL allows you to query the database in a variety of methods, all of which use English-like queries (we discussed some examples earlier). It’s utilized on websites for back-end data storage and processing (Facebook is a site that uses this). SQL will be used in music apps like Spotify, banking apps like Revolut, and other social networking networks like Twitter and Instagram, in addition to Facebook. Because SQL is the most widely used database language, it may be utilized by practically any firm that needs to store relational data. SQL queries are used to obtain data from a database, although their performance varies. Because many databases have their own system-specific additional proprietary extensions, this is the case.

SQL, in essence, provides CRUD capabilities for databases. What exactly does CRUD stand for?

  1. Create
  2. Read
  3. Update
  4. Delete


SQL command types

The language is divided into four types of SQL commands: DDL, DML, DQL, and DCL. Let’s take a closer look at each of these sections:

  1. DDL (data definition language) is a programming language that is used to build and change database objects such as tables, users, and indices.
  2. DML (data manipulation language) is a programming language that is used to delete, add, and edit data in databases.
  3. DCL (data control language) – used to control access to any data in a database.
  4. DQL (data query language) — This language is used to run queries on data and find information, and it is made up entirely of COMMAND statements.

There are tools available to assist you in writing SQL, such as Microsoft’s SQL Server Management Studio, DataGrip, Oracle’s SQL Developer, SQL Workbench, and Toad.


SQL versus NoSQL

NoSQL databases sprang to prominence in the late 2000s to accommodate data that required less upfront structure. These databases are typically easier for developers to use, with faster searches and more flexible data structures. SQL-based databases, on the other hand, are designed exclusively for relational data. They support flexible querying, are well-structured, and have a small data storage footprint. SQL databases are significantly more common than NoSQL databases, but they are routinely used in tandem.


There are some significant distinctions between the two, which include:

  1. Scalability – NoSQL databases are often horizontally scalable, whereas SQL databases are typically vertically scalable. As a result, NoSQL databases can frequently accommodate larger traffic volumes.
  2. SQL databases are table-based, whereas NoSQL databases might be graph-based, document-based, or wide column stores. Multi-row transactions are better suited to SQL databases.
  3. Knowledge and community — Because SQL is more widely used and has been around for a longer period of time, there is a wealth of information and communities available. Because NoSQL lacks this amount of forums and resources, it may be more difficult to obtain assistance when needed.


Types of SQL jobs

Learning SQL will provide opportunities in a variety of various occupations; let’s have a look at some of the possibilities:

Data scientist

A data scientist is an analytical data expert who extracts, analyses, and interprets large amounts of data from many sources in order to solve problems. SQL is essential for data scientists since databases are at the heart of their job due to the data analytics they must perform. If you want to learn more about this career option, have a look at this in-depth data science course.

SEO analyst

In order to enhance organic search traffic, an SEO analyst examines data and optimizes site content. SQL is useful for this profession since they work with a lot of massive data, and databases are significantly more powerful than excel documents, which are commonly used. If the concept of working as an SEO piques your interest, why not attempt our SEO and WordPress training course to get started?

Software engineer

A software engineer creates and maintains computer systems and application software. To construct software, a software engineer must have an understanding of programming languages, and most programmers must have some knowledge of SQL. If you want to be a software engineer, our ExpertTrack on software development fundamentals will walk you through the basics.

Business analyst

A business analyst examines data and documents market situations in order to provide advice on company decisions. This role is heavily reliant on SQL because it is data-intensive, and you will almost certainly be working with relational databases. Check out this excellent business analytics course to learn more about data for business. SQL is useful not only for getting into one of these positions, but it can also be useful for those who own a business or plan to establish one. Relational databases can assist you in storing, sorting, and modifying massive volumes of data.

How to learn SQL

Taking the initial step toward learning a programming language may appear difficult at first, but with patience and determination, you will be able to realize your full potential. Begin with the fundamentals and progress to more sophisticated instructions when you’re ready. Fortunately, there are numerous online courses and resources available to assist you in learning this valuable language. A free course, such as this introduction to databases and SQL, is an excellent place to begin. In addition to courses, watching video tutorials and becoming familiar with the methods and software utilized is an excellent approach to learning.


Practice is one of the finest strategies to retain any material you learn and recall the SQL commands. You can test your understanding by downloading a free SQL database management system, such as MySQL, and experimenting with the functions, and examining the database. SQL fiddle, for example, is a website that simulates a SQL administration system. You can experiment with making statements on sites like these without having to install any software. When you are confident in your SQL understanding, you can begin working toward a SQL certification. This will look excellent on your resume and will greatly increase your chances of landing one of the SQL jobs mentioned above.


Final thoughts

SQL is a very powerful language that might be good to learn if you want to upskill and be more efficient in your current work or if you want to find a new career. We hope that this essay has given you the confidence to go out there and begin studying the language for yourself. If you’re ready to begin your SQL adventure right now, have a look at our SQL for data analytics, data query using Transact-SQL, and preserving and organizing data courses.