What Is SQL? Definition and Benefits

By Indeed Editorial Team

Updated 21 August 2022 | Published 12 June 2021

Updated 21 August 2022

Published 12 June 2021

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Structured Query Language or SQL is a common programming language for relational databases. Many IT professionals like data analysts, database administrators, SQL developers and data scientists often require using this coding language. Having knowledge and expertise in SQL is important for these roles.

In this article, we define what is SQL and the five types of SQL queries, explain the benefits of learning this programming language along with tips for improving your SQL skills and list job roles that require knowledge of this language.

Related: Difference Between MySQL and SQL (With Definitions)

What Is SQL?

What is SQL, can be defined as a database coding language that extracts and manages data stored in a relational database. A relational database means you store and retrieve data in the form of relations or tables. For example, a table contains information about employees, such as employee id, name, contact number and department. This employee table is a relational database with only one relation called employee. You use SQL to communicate with a database. Using different commands, SQL tells the database what to do.

You can use the SQL commands to update, search, retrieve, add and delete data. Some of the standard and widely used commands are: Select, Update, Create, Delete, Group By and Insert. Though SQL is a standard of the American National Standards Institute (ANSI) and the International Organisation for Standardisation (ISO), many organisations use proprietary extensions based on the database used by the organisation. Furthermore, like other programming languages, SQL has a markup. This makes it essential for IT professionals to learn SQL markup.

Related: 11 Common SQL Interview Questions and Answers

5 Types Of SQL Queries

In your workplace, you are likely to use these five types of SQL queries:

1. Data definition language (DDL)

You can use SQL as a DDL. This means you can create a database, characterise its structure, use it and delete it when you no longer need it. DDL primarily deals with database description and schemas. The basic SQL commands under DDL are:

  • Create: Used for creating a new table or database

  • Drop: Used for deleting a database or an existing table

  • Alter: Used for altering the database structure

  • Truncate: Used for deleting all rows from a table and freeing up space in the table

2. Data manipulation language (DML)

You can use SQL as a DML. It means SQL can manipulate data in an existing database. The basic commands under DML are:

  • Insert: used for inserting data into a table

  • Update: used for updating or modifying values in a table

  • Delete: used for deleting records from a table

Delete command differs from the Truncate command. You cannot roll back the Truncate command, but you can roll back the Delete command. Truncate is faster than Delete. Also, using the Truncate command, you can delete the entire data from the table, while the Delete command only removes specific data.

3. Data control language (DCL)

DCL commands can grant and revoke the permissions of a database user. It includes commands like:

  • Revoke: used to take back permission from the database user

  • Grant: used to grant permission or access to the database user

4. Transaction control language (TCL)

TCL commands deal with transactions within a database. You can use TCL commands only with DML commands like Insert, Update and Delete. The basic commands under TCL are:

  • Commit: used for saving all transactions to the database

  • Rollback: used for undoing unsaved transactions in the database

  • Savepoint: used for rolling back a transaction to a certain point without rolling back the entire transaction

5. Data query language (DQL)

DQL fetches the specified data from the database. It only includes one command:

  • Select: Used for selecting the attribute based on the condition described by the Where clause.

Related: What Is a SQL Server and Other Frequently Asked Questions

Benefits Of Learning SQL

Here are four reasons why technical and non-technical professionals are required to learn SQL:

Higher growth potential

Knowledge of SQL can bolster your CV and help you get a job in the IT industry. It can also enable you to grow in your current company. As most IT jobs require knowledge of SQL, employers prefer candidates with excellent knowledge of databases. Furthermore, if you are well-versed in SQL and some other programming language like Python, Java or C++, you can negotiate a salary increase or promotion at your current workplace.

Related: SQL Career Skills (With Definition And Tips To Improve)

Improved communication

It can improve communication with clients and across teams. Mastery over SQL would allow both non-technical and technical teams to communicate without any SQL language barrier. For example, with knowledge of SQL, marketing teams can better communicate their database requirement to a database administrator (DBA). The DBA team does not require to spend hours deciphering the information, and they can provide marketing teams with what they want. It also reduces miscommunication and you can get things done faster.

Related: How To Improve Communication Skills

Improved visibility

When you know SQL, you can directly work with primary data rather than asking someone else to create a structured and organised dataset. This way, you can focus on your project, complete it on time and gain visibility by becoming a valuable technical asset. Also, when you use SQL in the skills section of your CV, you can increase your visibility to a potential employer. It is important because employers commonly use an applicant tracking system (ATS) to search for relevant keywords in your CV.

Related: What is a CV?

Secured future

SQL has its roots that extend back to the 1960s, and even today, the language is popular. Over these years, there have been some significant changes in the language structure, but most of it remains the same. When you learn SQL, you learn a language that is not likely to become outdated or extinct. This secures your career as SQL would remain an in-demand programming language of the database.

How To Learn And Improve Your SQL Knowledge?

SQL is one of the most important languages for IT professionals. Here the top five ways you can learn and improve your SQL skills:

1. Get a certification

Earning relevant certifications can develop your SQL knowledge and validate your qualification to the potential employer. Certification in SQL can help you stay up-to-date with the latest technology and development in this field. A certification can help you differentiate yourself from other employees.

2. Practice SQL commands

You can improve your SQL skills by practicing on free online programs. These online programs provide syntax for all commands. Start by creating a new table. Then add data points and update the table. The more you practice, the better you can perform at the workplace.

3. Document your SQL learning experience

As you practice different SQL commands, document your experience. When you write and document your learning experience, you are required to think, test and validate concepts you already know. It is a great way to refine your SQL knowledge.

4. Watch SQL tutorials

If you are short on time and want to learn SQL without investing in certification, you can watch SQL video tutorials online. Most of these video tutorials are short and self-explanatory. You can study them at your own pace. Additionally, you can skip and watch important portions. For example, you may know how to use DML commands, but you are not confident about using TCL commands. You can always skip the DML portion and study just the TCL portion.

5. Study in a group

When you study in a group, you can share ideas and knowledge within the group. This helps you understand how others might solve problems related to the database. To clear your doubts and to learn how to use the language in real-time projects, your group can take help from an experienced professional.

Related: SQL Query Interview Questions for Freshers and Experienced Candidates (With Sample Answers)

Job Roles That May Require SQL

Some positions that require knowledge of SQL are:

1. Quality assurance engineer

National average salary: ₹5,34,259 per year

Primary duties: They verify if a software system/program or web application meets the specified requirement. Quality assurance (QA) engineers also make sure the software produces the desired results. As software systems use a large amount of data, the QA engineers are required to validate the data from the database.

Related: Important Selenium Interview Questions and Example Answers

2. SQL developer

National average salary: ₹5,97,530 per year

Primary duties: These professionals use SQL to develop databases. They primarily work with other teams to understand the requirement of end-users. Based on the requirement, they develop databases.

3. Database administrator (DBA)

National average salary: ₹6,65,177 per year

Primary duties: These professionals manage and maintain a database. They make sure that the organisation's database and its related applications are functional and secure. A DBA also ensures that data available to users is safe from unauthorised access. They write SQL queries to enhance data performance.

4. Data scientist

National average salary: ₹8,43,360 per year

Primary duties: These professionals gather and analyse large sets of unstructured and structured data. They use SQL to query structured data from databases.

5. Data analyst

National average salary: ₹4,58,888 per year

Primary duties: They collect, refine and process information to improve business decisions. A data analyst uses SQL to access, read and analyse the data stored in the organisation's database.

Salary figures reflect data listed on Indeed Salaries at time of writing. Salaries may vary depending on the hiring organisation and a candidate's experience, academic background and location.

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