SQL – what is a simple language

SQL – in simple words, it is a programming language for structured queries (SQL, Structured Query Language), which is used as an effective way to save data, find its parts, update, extract from the database and delete.

It is pronounced as “Escuel “, but most often you can hear the slang “Sequel”.

The main tool for database optimization and maintenance is what SQL is for, although it is not limited to these goals. Processing capabilities cover view definition commands, access rights, relationship schemes (including their deletion and modification), interaction with other programming languages, integrity checks, start and end of transactions.

Why do you need SQL on a specific example?

For a layperson to understand what SQL means for the IT industry, let us give a simple example.

Imagine a table with information about students: names, age, subject of study, and so on. It has a certain number of rows and columns. One of the rows contains the progress of students.

As soon as all data are entered into the table, each entry falls into a different category (columns or “attributes”). This is an organized database. All information organized inside it, which can be managed, is called Database Schema.

If you want to grant scholarships to students who receive a grade of 90% or more, then a data query is performed in SQL, which in simple words means “to ask the database to provide information about students who receive 90% or more points.

The team will have a syntactic look:

SELECT * FROM Student WHERE Percentage>=90;

When the amount of data is small (say 10 students), you can easily calculate everything and write on a piece of paper. But when the amount of data increases to thousands of records, SQL becomes necessary – it helps to manage huge data efficiently, that is, to quickly get calculations based on them.

How is SQL used and what is its use?

Since 1974, when the language of structured queries first appeared, it provides interaction with database management systems (DBMS) around the world.

SQL, as a simple and easy to learn free software language, is actively used today:

• by database developers (provide application functionality),
• by testers (in manual and automatic mode),
  administrators (perform environment maintenance).

The language is universal and has a well-defined structure due to well-established standards. Interaction with databases is fast even in situations where the data volumes are large (Big Data). In addition, efficient management is possible even without much knowledge of the code.

Areas of application and where SQL is used:

SQL DDL

As a Data Definition Language (DDL), it allows you to independently create a database, define its structure, use it, and then reset it after the end of manipulations.

SQL DML

As a Data Management Language (DML) – to support existing databases in a labor- and performance-efficient language for input, modification, and extraction of data in relation to the database.

SQL DCL

As a Data Control Language (DCL) when you need to protect your database from damage and misuse.

SQL client/server

Opens a single-sign-on system (SSO) with user authentication in multiple web applications within a single session.

Three-level SQL architecture

Guarantees protection of information components from unauthorized use and digital copying.

Almost all relational databases use SQL. Some of them even have a language abbreviation in their name: Microsoft SQL Server, MySQL, PostgreSQL, Non Stop SQL, SQLite. But there are also those that are called independently, like Oracle, DB/2, Ingres. There are also “NoSQL” – is a collective term that refers to all non-relational databases without SQL (or when it is not the only query language).
In MySQL, question marks instead of Russian letters are a solution to the encoding problem.

Video lecture on how and where exactly SQL is used, as well as how databases work in real conditions:

What is SQL? [in 4 minutes for beginners]