Introduction to SQL: what is SQL and how to start learning SQL?

Time:2022-1-14

preface:

In our daily life, we use a large number of applications, gadgets and devices. A lot of data is generated every second. SQL provides a standard way to process such data. Through this article, I will explain to you what SQL is and the concept of its evolution.

Introduction to SQL: what is SQL and how to start learning SQL?
This article will discuss the following topics:

Problems with traditional file systems

Since the computer age, data storage has become one of the main issues concerned by people. Previously, we usually stored data in file based systems, which led to improper data management. Although it seems well organized, it also has its own internal defects:

Introduction to SQL: what is SQL and how to start learning SQL?
1. Data redundancy

When the same data is stored in different places of our computer system, there will be duplicate data. In the file system, there is no real-time check for duplicate files. This will increase the size of the structure and lead to a lack of security functions. Therefore, the file system is very vulnerable in nature.

2. Limited data sharing and lack of security

Data sharing is closely related to security. Sharing data among multiple geographically dispersed users will bring many security risks. For spreadsheet data and other documents, the built-in file system program provides basic security, but few people use it or know it at all.

Security and data sharing features are usually unlocked when creating data management and reporting programs, so they are often ignored in file system environments. These functions include effective password protection, the ability to lock some files or some systems themselves, and other measures designed to protect data confidentiality. Even when they are used, they are not enough to achieve reliable data sharing among users.

3. Difficulty in answering quickly

Another important problem in the traditional file environment system is that it is difficult to get the answer quickly, because it needs more temporary queries and more programs to process, so it needs to respond in time.

4. Data dependency

In the file system, files and records are composed of specific physical formats, which are encoded into applications by programmers. If the format of any record is changed, we need to ensure that all remaining record formats are updated. This information must also be updated in the system. Any change in the storage structure or access method can greatly affect the processing or results of the application.

Due to all the above shortcomings and other limitations, a new technology needs to be implemented, so SQL came into being.

Development of SQL

SQL was developed by Donald Chamberlin and raymondf Boyce at IBM in the 1970s. It was originally called sequence, but it was later changed to SQL. It was renamed because sequence is the name of a British engineering company. In SQL, data is stored in relational form. This relationship theory was proposed by Boyce and Chamberlin.

It was not until a few years later that the SQL language was made public. The first company to release a modified version of SQL was relational software, Inc. (now Oracle), which is called Oracle v2. Since then, the American National Standards Institute (ANSI) and the international standards organization took SQL language as the standard language for relational database communication. Nowadays, SQL is recognized as the standard language of relational database management system.

So, what isSQL?

Introduction to SQL: what is SQL and how to start learning SQL?
Structured query languageThe pronunciation of structured query language (SQL) is “s-q-l”, sometimes it can also be “sequel”, which is the standard language for dealing with relational databases. Let’s take another practical example to understand what SQL is.

If two people want to communicate with each other, they must use a language that both sides can understand. If we consider these two people, one as a user and the other as a database, the language used for communication between the two is called SQL. Similarly, how a language has syntax and various rules to guide its use, and even SQL has its own instructions.

SQL is effectively used to insert, search, update, delete and modify database records. This does not mean that SQL cannot do anything beyond this scope. In fact, it can also do more other things.

Now that we know what SQL is, let’s look at its processing functions:

  • DDL (data definition language) provides SQL commands for defining relationship patterns, deleting relationships, and modifying relationship patterns.
  • Data processing language DML provides a query language based on relational algebra and tuple calculus.
  • Embedded DML is used for general programming language.
  • DDL contains commands for defining views.
  • The DDL command specifies access to relationships and views.
  • SQL provides integrity checks.

Introduction to SQL: what is SQL and how to start learning SQL?
Let’s look at some of the most popular basic queries in SQL.

Create database: the syntax of this database is

create Database database_name;

Delete the created database:

drop Database database_name;

Create a table in the database

create Table table_name;

Delete previously existing tables

drop Table table_name;

Therefore, if you want to learn more about SQL queries, please take a look at my article on the basics of SQL, which will help you start using SQL

Advantages of SQL

Now that we know all about SQL, it’s time to understand its advantages.
Introduction to SQL: what is SQL and how to start learning SQL?
1. SQL has well-defined standards

As it says, SQL developers have mentioned how to write each query. When writing queries, there is no room for ambiguity and standards must be followed.

2. Easy to learn

=SQL is a language used to process databases. Because SQL has a huge user base and well-defined standards, it is really easy for beginners to learn.

3. In SQL, we can create multiple views

This is one of the unique and early features of SQL. The view is only to create a virtual table. The virtual table is a temporary table for some purposes. This can protect the integrity of data. SQL can create not only one view, but also multiple views.

4. SQL queries are portable

This means that we can execute SQL queries in one system and the same query in another without changing the format. However, the condition is that the environment settings of these systems must be the same, otherwise the query will not be executed

5. It is an interactive language

The main purpose of SQL is to communicate with the database. We can write complex queries to obtain results from the database. Anyone can easily understand these queries.

Now let’s look at some of its real-time applications

Real time SQL

Since SQL is a language used to operate databases, we need to focus on the overall situation of the data management industry. The database mentioned here also includes SQL language. The database can be used in many industries, such as e-commerce, medicine, clubs, libraries, video websites, beauty salons, travel agencies, operators, government agencies, etc.

1. Financial industry

Real time management of funds, assets, stocks, etc. is a tedious task. SQL and database technology are helping the financial sector complete its primary task. SQL query can also be used to check fraud activities.
Introduction to SQL: what is SQL and how to start learning SQL?
2. Education sector

In schools, colleges and universities, database systems are often used to store and retrieve data about student details, Faculty details, course details, examination details, payroll data, attendance details, expense details, etc. it is necessary to efficiently store and retrieve a large number of interrelated data.

Introduction to SQL: what is SQL and how to start learning SQL?

3. Health care sector

In hospitals and medical institutions, maintaining data related to doctors, patients and staff is a huge task. The effective coordination among the three must be handled seamlessly. With the help of SQL and database, this industry has achieved great development.

Introduction to SQL: what is SQL and how to start learning SQL?
4. Retail

In the retail industry, customer data must be managed effectively. No errors occur when processing data. With the help of SQL and database system, retail industry can not only ensure the security of data, but also carry out real-time analysis.

Introduction to SQL: what is SQL and how to start learning SQL?