How to learn SQL (step-by-step guide) in 2021
Table of Contents
- What is SQL?
- Problems with Traditional File System
- Importance of SQL
- Why Should You Learn SQL in 2021?
- Career in SQL
- Prerequisites to Learn SQL
- How to Install SQL?
- IDEs for SQL
- Online Compilers
- Roadmap to Learn SQL
- SQL Courses and Tutorials
- Top Free Resources to Learn SQL and DBMS
- Learning SQL from Documentation
- Top SQL Projects for Beginners
- Best SQL Certifications
- SQL Interview Questions
- Wrapping Up!
With the gradual shift in digital technology in recent years, trillions of bytes of data are being generated every second. It has been rightfully said by some of the experts that - “Data is the new oil!”. The data generated by the users come in various forms - these are generated through social media browsing, binge-watching movies, shopping through online portals, online banking transactions, etc.
So what’s the use of such large volumes of data? These data are organized as per the needs of companies to carry out targeted ads to attract customers to see and buy their products. This data is used to analyze the customer’s behavior to improve user experience to increase their sales or shoot up their service quality.
However, the generated data is highly unorganized and needs to be cleaned before the experts can analyze it. Also, storing such huge volumes of data is another big task to handle. Nowadays, several big data solutions help companies store, organize, and analyze large volumes of data. But what about the already structured data that comes from the websites. These include your login/signup details, credit card details, user-profile details, online purchasing history, etc. These data can be reused by the companies when you visit their website the next time. To reuse it, it’s obvious that they need to store it somewhere in a secured place.
Large server nodes are set up either on the cloud or physical machines with huge databases where such data is stored. Now, several types of databases can be used for different purposes. And to manage the different types of databases, one needs a certain set of database management skills. Let’s discuss the different types of databases first.
1. Hierarchical Database
This type of database has a tree structure where they have a parent node, and each parent node has several child nodes linked with branches. The parent nodes represent the higher-level data, and the child nodes represent the lower-level of information, and the branches represent the relationship between these nodes.
2. Object-Oriented Database
This type of database has key components such as classes and objects. Objects can be defined as real-time instances of the classes. They hold records or actual data to be stored. The classes have functions, methods, or variables that define the operations to be performed on these objects or data.
3. Network Database
This type of database has a network structure. It supported many-to-many relationships between the nodes and was designed to solve the problems with a hierarchical database.
4. Relational Database
In such databases, data is stored in records or tables whose columns define the type of data, and the rows contain the actual piece of information. Tables can form relationships with other tables based on conditions.
The most common type of database used across organizations to store data in an organized, secured, and robust manner is the relational database. Relational databases are highly scalable and flexible when it comes to accessing certain sets of information. SQL or Structured Query Language is a programming language used to query relational databases and find out records or information from the tables.
What is SQL?
As discussed earlier, SQL is a programming language that you can use to query data in relational databases. You can create, update, modify, delete, and perform other operations on the tables in relational databases. SQL is a declarative language, or in other words, it’s a procedural language. This means that the user can specify what type of data instead of specifying it and getting the data.
Problems with Traditional File System
Before the invention of SQL or other databases, data was stored in file systems with lots of uses related to data mismanagement. Even though we think that file systems look neatly organized, there are multiple flaws associated with them when storing, accessing, and modifying continuous volumes of data. Let’s discuss a few of them.
1. Redundancy of Data
Data redundancy means that the same information is stored in one or more places, leading to unnecessary storage space usage. In the case of file-based databases, there was no way to look out for duplicate files. Also, consequently, the file system becomes exposed to security hazards and information leaks.
2. Data Dependence
In file systems, there’s a specific structure that needs to be followed. If we change any record’s format, we need to update all the data formats dependent on it. Moreover, changes in the structure of file-system-based databases largely impact the performance of the applications.
3. Data Sharing
Sharing of data was a major issue in file systems as it would lead to major security risks. Even if we used security measures such as encrypting files, password-protecting them, locking out portions of it, etc., these measures are not robust enough to ensure complete security.
Due to all the above-mentioned reasons, there was a strong need to create a new form of data storage to address all these problems.
Importance of SQL
Let’s take a look at a few important points that made SQL such a popular querying language.
1. Popular Among Professionals
It’s universally adopted experts, and professionals turn to SQL without a second thought when handling and organizing data. All the popular open-source and free databases support SQL to query information.
2. Easy to Learn
The syntax of SQL is similar to simple natural language and is quite easy to learn when compared to the complex syntaxes of other programming languages such as Java, C++, etc.
3.Handle Large Sets of Data
Compared to excel and spreadsheets, SQL can easily handle large datasets with minimal effort required to manage them.
4. Better Insight Into The Datasets
To retrieve useful insights from data, you need to understand the data better. SQL allows you to use commands to obtain relationships between the datasets to understand them better.
SQL is a query language that both ISO and ANSI have standardized. It’s quite stable, with no big updates in syntax, and once you learn it, you don’t need to focus much on newer releases.
6. Hot Skill
Doesn’t matter if you want to work in data science, machine learning, database management, data analysis, etc., SQL is a common skill and has a great demand in the job market.
Why Should You Learn SQL in 2021?
Let’s skim through a few points that would allow you to understand why SQL is one of the most important skills to get your hands dirty on to stay up-to-date with the top skills and technologies.
- It has lots of processing capabilities which are defined into sets such as Data Definition Language (create, alter, and delete schemas), Data Manipulation Language (update, insert, delete, retrieve tables), Data Control Language (revoke permissions or grant them).
- It allows you to perform integrity-checking on the databases and normalize the databases to remove data redundancy and other problems related to file-system-based databases.
- Just using a single line of command, you can retrieve highly filtered data along with multiple records.
- Once you get handy with the language, you can use complicated queries to get better insights into the data.
- It has an easy syntax, is highly scalable, provides high security, and has a large community.
- It is interactive, highly portable, can create several views of a table to work and experiment on, and has a well-defined standard.
Career in SQL
Tons of jobs and careers require SQL as a skill in data-centric organizations. These organizations seek SQL professionals who can apply their analytical thinking with SQL to provide better insights on huge chunks of data. If you are a candidate who has a knack for working with data and manipulating it, you should definitely seek a career in SQL programming. The job market related to SQL can be found on cloud-based organizations and those who use databases on-premises.
- Qualifications that the recruiters seek in an SQL professional may vary from company to company. It largely depends upon the ROI, client requirements, job type, etc.
- The basic educational qualifications include a bachelor’s or master’s degree in computer science engineering, IT, or even specialization courses in the IT domain.
- Additional certifications such as Database developer, administrator, designer, architect, etc., will add colors to your portfolio and grant you an upper hand over thousands of other candidates.
- Experience in PL/SQL, ETL, etc., would be beneficial.
- SQL Server stands as the 3rd most popular database server, and millions of professionals are currently working on different roles that directly or indirectly require SQL as a skill.
- Top career paths in SQL include - Database Administrator, Business Intelligence Professionals, Data Scientists, Database Developers, Database Testers, ETL Developers, BI Application Developers, Big Data Experts, Cloud Database Engineers, Database Migration Engineers, etc.
- The average salary of a SQL professional depends hugely on the career paths that he chooses. Usually, professionals with 5+ years of experience working with SQL have a higher average salary than freshers.
- According to a report by payscale in 2018, the average salaries for SQL developers in the US is around USD 65k, for Senior SQL Developers is USD 85k, for Senior Database Administrators, it is around $100k, for production DBA, the average salary can be as high as $130k.
Prerequisites to Learn SQL
To start learning a query language like SQL, you must know the following areas.
- Database Management Systems.
- DBMS concepts like normalization, ACID properties, transactions, etc.
- ER diagrams, relational models, and all about relational databases.
Apart from this, one should have good analytical skills and understand storing data in organized relational databases to generate useful insights from complicated queries through SQL.
Please note that even if you don’t have a background in Computer Science or IT and don’t have prior knowledge of Database Management Systems, you don’t need to worry. We will provide you with all the resources, courses, tutorials, and documentation that you will need to learn the concepts right from basic to advanced level later on in this article. So, please stick with us till the end.
How to Install SQL?
Let’s see how to install SQL Server in your Windows machine that will help you to write SQL queries such as creating databases, tables, inserting data inside tables, modifying and updating the data, etc.
You can download Microsoft SQL Server from the official Microsoft Website.
The latest version currently is SQL Server 2019. Please note that Microsoft allows you to download two free editions of the SQL Server. They are Developer and Express editions. The MS SQL Server Developer Edition has all the required features, but the problem with that is we can’t use it for production. However, the other free edition called MS SQL Server Express edition can be used for production but has limited features. For those who want to learn SQL, it is best, to begin with, the developer edition.
Press the Download Now button. This will download an executable file that you can run to install the SQL Server. Once the installation has started, it will ask you to choose one from three different types of installation - Basic, Custom, and Download Media. The Basic option automatically chooses all the basic packages that you will need to start working with SQL Server. The Custom option will allow you to choose your own packages, and the Download Media option will allow you to download all the packages and later install them on a different machine.
We will choose the basic option. After that, accept all the licensing agreements, choose the install location, and install the Server. After it has been successfully installed, you can click on the Connect Now button to start executing your queries.
IDEs for SQL
An IDE or Integrated Development Environment is a graphical tool that allows you to manage all your application-related files and work with useful packages, auto-complete features, syntax-highlighter, etc., to make your development experience better.
While it’s true that you can create and manage databases and tables right from the Command Line itself, using an IDE will always be helpful to get a birds-eye view of all the databases, queries, tables, and other components. In fact, some IDEs have a help section to explain to you the basic commands and their uses. You can just fill the text fields, choose the various pre-formatted commands, click on the Ok button, and your work will be done. It’s as simple as that. Moreover, some IDEs allow you to backup and restore databases and tables as well.
Hence, it’s always a wise decision to select an IDE that caters to your requirements before you get your hands dirty with SQL. Here’s a list of top IDEs that you can utilize to compose complicated SQL queries.
DBeaver is an open-source, Java-based database IDE. It’s free to use and has power-packed features that will give you a smooth development experience.
- It allows you to export tables to CSV files and dump, restore the tables as well.
- It lets you save the most frequently used SQL commands. You can load these saved commands later on for other projects.
- It has several color themes as well.
- It has a session management tool.
- It allows you to compare two DB tables and their structures.
- Queries that have been executed are displayed aesthetically in a separate interface.
- It allows you to edit cells of the database tables and commit them graphically.
PHPMyAdmin is a feature-rich, HTML-based, open-source tool that you can use to manage your databases.
- It allows you to manage users and permissions.
- It can support a plethora of languages.
- It allows to create and edit queries and columns of the resultant rows.
- You can save your queries for a later time.
- The IDE is highly configurable to hide or show tables, comments, charsets, timestamps, etc.
- You can create backups of the databases, convert them to CSV files, import SQL dumps, etc.
- It allows you to administer multiple servers.
- You can use QBE to create complicated queries.
Adminer can be used as an alternative to PHPMyAdmin. It is web-based, supports tons of plugins, lets you work with multiple databases such as Oracle, SQLite, etc.
- Connect to databases, create new ones, etc.
- You can print the schemas of databases even if foreign keys connect them.
- You can set and manage user permissions and rights and even change them as an admin.
- The help section is quite good; you can display variables that have referral links to documentation.
- You can easily manage partitions of tables and events.
If you don’t want to go through the hectic processes of downloading SQL Servers and installing them, downloading and installing IDEs, you can always use one of the tons of online compilers that are available on-demand. Some of the most popular online compilers for SQL are - mycompiler, tutorialspoint, and JDoodle.
Roadmap to Learn SQL
Having previous knowledge of Database Management concepts and relational databases might be helpful. However, you don’t really need to know them to get started with SQL. Here’s a complete roadmap that will help you get started with SQL.
- Start with learning the basic concepts of database management such as databases, transactions, relational models, normalization techniques, tables, different keys in schemas, etc.
- After you have learned the basics of database management, you can go ahead and start learning the basic topics and concepts of SQL. Some of them are -
- SQL Syntax, data types, variables, etc.
- Select, Where, And, Or, Not, Order By, commands.
- Insert, Update, Delete commands.
- Min, Max, Count, Average, Sum, commands.
- Like, In, Between, Top, Group By, commands.
- Joins such as Inner, Outer, Left, Right, Full, Self joins.
- SQL having, exists, any, all, case, null functions, etc.
- SQL database-related commands such as create, drop, backup, etc.
- SQL table commands such as create, alter, update, drop, etc.
- SQL constraints such as not null, unique, check, default, auto-increment, etc.
- SQL keys such as primary, unique, foreign, etc.
- SQL advanced concepts such as Views, Triggers, Functions, PL/SQL, Injection, Hosting, etc.
- After acquiring knowledge on all the above topics, you can start creating databases and tables and executing the commands you have learned in theory.
If you follow this roadmap, you will learn the concepts of the database as SQL comma, which will definitely help you get a good overview of the entire database management concept to help you get an edge over other candidates to secure a good career DBMS.
You can also read the SQL Cheat Sheet to get a quick understanding of the roadmap.
SQL Courses and Tutorials
Here’s a list of online courses and tutorials that you can use to learn SQL in a more detailed and hands-on manner. Using these courses will provide you with a clear guide and pathway to be taken and some projects to enhance your portfolio and get you started with your career.
- This is one of the most detailed courses that you will come across. To get started with this course, you don’t need to have any previous knowledge of databases, SQL, or MySQL. It’s for complete beginners. However, if you have previous programming experience, you will be able to understand the concepts better.
- It will take you through detailed concepts with hands-on, real-world projects that will help you learn the concepts better. Once you complete this tutorial, you can easily develop and build complex databases.
- You will be able to create databases, use existing ones, and interact with them.
- Writing complicated SQL queries will be a piece of cake for you.
- You will build a web application using MySQL and Node.
Resources - 20 hours of video, 141 articles, 4 resources, certificate.
Price - INR 8640
Rating - 4.6 by 51,134 ratings.
- This is a specialization provided by Duke University through the Coursera platform. This specialization consists of 5 courses. With the help of this course, you will be able to turn data into valuable insights and drive change in business processes by analyzing key metrics.
- You will learn how to manage big data with Excel and SQL and perform analysis on such large volumes of data. You will also learn data visualization techniques using tableau.
- You will be able to manage big data using MySQL and Excel.
- You will learn data visualization using Tableau.
- You will master data analysis.
- You will create models, forecasts, designs, and perform analysis.
- You will work on a real-life project.
Resource - 5 courses, Approx 7 Months of Content.
Price - INR 3576 per month.
Rating - 4.6 by 18,019 ratings.
- This is a self-paced course by EdX that will cover all the topics related to databases and SQL from beginner to advanced level. It is taught and led by industry experts and will help you build database programming skills to advance your knowledge. Through their lectures, you will learn how to build an SQL database; you will learn the fundamental basics of databases, etc.
- You will learn how to create SQL queries to perform CRUD operations in a database.
- You will learn concepts such as referential integrity and integrity constraints.
- You will draw data models such as ER and apply SQL queries to schemas based on these models.
- You will be able to learn procedures, triggers, functions, etc.
- You will understand concurrency control.
Resource - 4 months of content with 6-8 hours per week. Articles, Video tutorials, quizzes.
Price - INR 33144.
Rating - 4.5.
Take a look at some of the top SQL Certifications that will help you to shoot up your career in 2021.
Top Free Resources to Learn SQL and DBMS
Apart from all the costly online courses and tutorials that we have discussed above, you can also leverage some of the top free resources available online to learn the concepts of SQL and DBMS in a detailed manner. Some of the top free resources are -
DBMS Online Resources
- DBMS for GATE Exams - by TutorialsPoint
- DBMS Tutorial - by JavaTpoint
- DBMS Tutorial: A Complete Crash Course on DBMS - by Edureka
SQL Online Resources
- SQL Tutorial - by W3Schools
- Intro to SQL: Querying and managing data - by KhanAcademy
- SQL Tutorial - by TutorialsPoint
Learning SQL from Documentation
Apart from all the above-mentioned online paid and free courses and tutorials, you can also refer to the official documentation provided by Microsoft that will help you learn SQL in the best possible way. Documentations provide details about commands and concepts in the most detailed manner, explaining the concepts and their uses from unbiased perspectives. Check out the official Tutorials for SQL Server by Microsoft.
Top SQL Projects for Beginners
The best way to learn any programming concept is to get started with projects rather than just mugging up the theory and syntax. Projects help you figure out solutions to problems that you will face in real-world situations. They will give you deeper insights on the topics; it will help you apply your theoretical knowledge to create awesome products and obviously boost up your resume and portfolio.
Projects are verification of your skills. To start as a beginner, you should begin with small projects with fewer features and modules so that when errors pop up, you don’t give up. After building several small projects, you can add extra features to those projects or build a new complex project altogether.
Here’s a list of top beginner SQL projects.
1. Library Management System
You can create a simple web application connected to an SQL database where you have stored details related to books such as author, price, publications, content, genre, etc. You can create a portal where students, researchers, and faculties can use their ID cards to register books for a specific period of time, issue fines if the books are not returned within the timeframe, create a payment portal, create another database to store users profile details, etc.
2. Online Retail Application
You can create another web application that allows users to create profiles, display a list of items and price details, vendor details, etc., allow them to add products to their cards, add credit card information, make purchases, track delivery, etc.
3. Railway Ticket Booking System
You can create a platform that allows users to book railway tickets and has features such as user login, payment feature, display a list of trains between locations and their timing, the number of seats available, the train routes, etc.
4. Hospital Management System
You can partner with a clinic or create a standalone application that allows patients and doctors to interact and consult with each other through video conferencing, prescribe medicines, pay fees, manage appointments, schedule calls, display a list of medicines and their information etc.
5. Human Resource Management System
You can create another application that allows small companies and organizations to manage their human resources. It keeps track of their employees and their performance, including pay scale, department, duties, timings, projects assigned, and other important pieces of information.
Have a look at our guide on top SQL projects.
Best SQL Certifications
After you have gained detailed insights on the theoretical concepts and practical concepts, the next step is to create a portfolio that will highlight your SQL skills during interviews. You have already done a few projects in SQL, and the next step is to get accredited and verifiable certifications by official vendors of SQL. A few accredited SQL certifications are -
- MTA: Database Fundamentals
- MCSA: SQL Server 2012/2014
- MCSA: SQL 2016 Database Administration
- MCSA: SQL 2016 Database Development
To get detailed information on these certifications along with other top certification courses, you can visit this guide on Top 5 SQL Server Certifications to Boost Your Career.
SQL Interview Questions
After having prepared with all theoretical and practical concepts of SQL, projects, certifications, etc., the time has come to prepare for the big day. You can now confidently move ahead to the next and final step to start preparing for SQL-related questions to ace your interviews with flying colors. When you sit for the interview, always remember to support all your theoretical answers with practical and real-life scenarios.
Here’s a list of top SQL interview questions.
- Question: Differentiate between conventional database models and relational database models?
- Question: Is it possible to inject PL/SQL in code snippets of SQL?
- Question: What do you mean by DML and explain some of its operations.
- Question: Explain joins and the different types of joins.
- Question: Explain the concept of ACID in SQL transactions.
- Question: Can you explain dateadd term that is used in SQL?
- Question: Fundamental differences between MySQL and SQL.
- Question: Is it possible to use the WHERE clause and TRUNCATE simultaneously?
- Question: Define COMMIT
- Question: Distinguish between a table and a field in SQL.
You can get a complete list of SQL QNA here.
- In this guide, we have started with a basic introduction to SQL and databases, and we have also discussed the different types of databases as well. We have discussed what SQL is and the problems with the traditional file systems. We have also discussed the importance of SQL and why it remains a trending job in the current market.
- We then skimmed through a few reasons why you should learn SQL in 2021 and discussed several career opportunities in SQL as well. We also discussed the prerequisites to learn SQL and install the SQL Server in a Windows machine.
- Moving on, we discussed a few top IDEs and online compilers that you can leverage to improve your SQL programming experience. We quickly discussed a detailed roadmap that would help you learn SQL and a few online paid and free courses and tutorials. We also discussed how to effectively use documentation to learn SQL in the best possible way.
- Post that, we discussed how to improve your portfolio by doing projects, grabbing accredited and verifiable certifications, and improving preparation for interviews with a curated list of top SQL interview questions.
We hope that through this detailed guide, you will get a complete and precise roadmap to learn SQL in 2021.
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