SQL (Structured Query Langauge)

SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system, or for stream processing in a relational data stream management system. SQL is an abbreviation for ‘Structured Query Language’, and pronounced either see-kwell or as separate letters.

SQL offers two main advantages over older read-write APIs such as ISAM or VSAM. Firstly, it introduced the concept of accessing many records with one single command. Secondly, it eliminates the need to specify how to reach a record, e.g. with or without an index.

SQL is a standardized query language for requesting information from a database. The original version called SEQUEL (Structured English Query Language) was designed by an IBM research center in 1974 and 1975. SQL was first introduced as a commercial database system in 1979 by Oracle Corporation.

Historically, SQL has been the favorite query language for database management systems running on minicomputers and mainframes. Increasingly, however, SQL is being supported by PC database systems because it supports distributed databases. This enables several users on a local-area network to access the same database simultaneously.

Is SQL a programming language?

SQL is a database management language for relational databases. SQL itself is not a programming language, but its standard allows creating procedural extensions for it, which extends it to the functionality of a mature programming language.

SQL itself consists of four principal sublanguages/commands:

  • DDL (Data Definition Language) is used to define data structures stored in the database. DDL statements allow us to create, modify or destroy individual database objects. Object types allowed depend on the DBMS used, and usually include databases, users, tables and some smaller housekeeping objects like roles and indexes.
  • DML (Data Manipulation Language) is used to query and change data stored in the database. DML statements allow us to select, insert, update and delete data in the tables. Sometimes pure select statements are not classified as part of DML since they don’t change the state of the data. All SQL DML statements are declarative.
  • DCL (Data Control Language) is used to control access to data stored in the database. DCL statements operate with privileges and allow them to grant and revoke privileges on applying certain DDL and DML commands to certain database objects.
  • TCL (Transaction Control Language) is used to control the processing of transactions in the database. Usual TCL statements are committed to applying the changes introduced by the transaction, rollback to undo them and savepoint to divide the transaction into several smaller parts.

Note that SQL implements declarative programming paradigm: each statement describes only the required action, and it’s up to DBMS to decide how to implement it, i.e., to plan the elementary operations necessary to perform the action and to execute them. However, the developer needs to understand the way DBMS analyzes each statement and creates its execution plan to be able to use SQL efficiently.

Top SQL editors:

  • Microsoft SQL Server Management Studio
  • MySQL Benchmark
  • Oracle SQL Developer
  • deForge Studio
  • DBeaver
  • SQLite Studio
  • SQuirreL SQL
  • HeidiSQL
  • RazorSQL


We live in an era where data is the most valuable asset and it’s being put at heart of every decision making process. Despite the explosion of NoSQL in recent years, SQL is still making its way back to become the universal interface for data analysis once again.

SQL is a popular way to get information out of relational database systems. Relational databases are set up with a particular structure – each record has a series of keys that are linked to one another in inconsistent ways and placed in a “table” represented visually in a grid.

Why do we need SQL?

  • We have a long list of tool, that is dependent on SQL
  • SQL is widely used in all Business Intelligence Tool
  • All databases depend on SQL
  • If you want to learn Big Data tools: Hive, Impala, Spark SQL depends on SQL
  • Data Science tools also depend on SQL
  • Data manipulation and data testing is done through SQL
  • It is very easy to learn SQL
  • SQL is one of the most sought-after skills by hiring employers


Advantages of SQL:

  • Data Security: MySQL is globally renowned for being the most secure and reliable database management system used in popular web applications including WordPress, Drupal, Joomla, Facebook, and Twitter.
  • High Performance: MySQL features a distinct storage-engine framework that facilitates system administrators to configure the MySQL database server for a flawless performance.
  • Round-the-Clock Up-time: MySQL comes with the assurance of 24×7 up-time and offers a wide range of high-availability solutions, including specialized cluster servers and master/slave replication configurations.
  • The Flexibility of Open Source: All the fears and worries that arise in an open-source solution can be brought to an end with MySQL’s round-the-clock support and enterprise indemnification. The secure processing and trusted software of MySQL combine to provide effective transactions for large-volume projects. It makes maintenance, debugging and upgrades fast and easy while enhancing the end-user experience.


Disadvantages of SQL:

  • Difficulty in Interfacing: Interfacing a SQL database is more difficult than including a couple of lines of code. Even though SQL databases complete with ANSI and ISO measures, a few databases go for restrictive augmentations to standard SQL to guarantee seller secure.
  • Partial Control: The developers who use SQL does not have full control over the database as a result of the concealed business rules.
  • Implementation: A portion of the databases goes to the restrictive augmentations to standard SQL for guaranteeing the vendor secure.
  • Cost: The working expense of some SQL versions makes it troublesome for a few software engineers to get to it.



Our main goal in this blog was to introduce you to the SQL. To do that, we wanted to present some of the key concepts related to working with SQL and help you build strong mental models around those concepts. The breadth and scope of the SQL commands provide the capability to create and manipulate a wide variety of database objects using the various CREATE, ALTER, and DROP commands. Those database objects then can be loaded with data using commands such as INSERT. The data can be manipulated using a wide variety of commands, such as SELECT, DELETE, and TRUNCATE, as well as the cursor commands, DECLARE, OPEN, FETCH, and CLOSE. Transactions to manipulate the data are controlled through the SET command, plus the COMMIT and ROLLBACK commands. And finally, other commands covered in this chapter include those that control a user’s access to database resources through commands such as GRANT and REVOKE.