What is Structured Query Language (SQL) - SQL Tutorial Guide

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SQL, or Structured Query Language, is a tool we use to work with database information. In addition, it has already connected to a database and requests the necessary data, organizes it, or makes changes. This article will help you understand the basics of SQL – what it is, how it works, and why it's useful. We'll go through the essential parts of the language, show you examples, and talk about how people use it.

Meaning of Structured Query Language

People have been using SQL since the 1970s. Additionally, it is a tool used by those who work with databases, like computer wizards and data analysts. We'd like to give a brief introduction to relational databases before we proceed further.

These databases are known as 'relational' because they contain tables that relate to each other. One table might have names and addresses of customer services, while another keeps track of typical purchases, product codes, and customer contacts. They're all linked concurrently using a specific ID, like a secret code.

What Can SQL Do?

• SQL can ask database questions and get answers.
• It can grab data from databases.
• SQL can put new records into a database.
• SQL language can also update existing records in a database.
• It can remove records from a database.
• It can create brand-new databases from scratch.
• SQL can assemble new tables in RDMS.
• It can make stored procedures to remember special instructions.
• SQL can create views in a database.
• It can set rules for who can do what with tables, procedures, and views in a database.

Here, we’ve discussed what SQL can do. We will learn about the Structured Query Language’s commands and Syntaxes further.

SQL Commands And Syntax

SQL is a database language. In other words, it uses unique code that helps us ask questions, make changes, and get information from organized data called relational databases.

Types of Commands

• Data Definition Language (DDL): It gives instructions on how tables should look.
• Data Manipulation Language (DML): This is for playing with the data inside the tables – adding, changing, or removing stuff.
• Data Query Language: It requires one command, SELECT, to grab specific data from tables.
• Data Control Language: Used to decide who gets access to what.
• Transaction Control Language: Used for making sure changes to the data are saved or canceled.

The following section will contain the syntax of the SQL query language.

How Do SQL Sentences Look?
 

• Sentences start with a command (like SELECT) and end with a semicolon (;).
• You can use big or small letters, but it's easy to write commands in all caps and names in lowercase.
• Sentences can be as short or as long as you want.

Example:
 

SELECT name, telephone, age

FROM customers

WHERE age > 21;

This code selects names, telephone numbers, and ages from a table named 'customers' but only for people older than 21.

In other terms, SQL helps us talk to databases, ask them questions, and tell them what to do with their data.

SQL Commands With Examples

Now, we will learn about some examples of structured query language.

We all know that SQL is a programming language for databases. Moreover, it uses different commands to do additional stuff. Here are some commands and how do they work:
 

1. SELECT

• Use it to pick and choose data from a table.

Example: "Show me titles, authors, and publication dates from the catalog where the date is 2021."
 

2. CREATE

• Make something new, like a whole new database or a table inside one.

Example: "Create a database called Human_Resources."

Also, you can create tables:

Example: "Create a table called Employees with columns for employee_ID, last_name, and first_name."
 

3. DELETE

• Erase stuff from a table. For example, "Delete all info about employees with the last name Smithee."
   

4. INSERT INTO

• Put new info into a table. Like, "Add a new employee named Alan Smithee."
   

5. UPDATE

Change things in a table. For instance, it says, "Update all records where the last name is Smithee to say Smith.”

Here, we’ve covered all examples of structured query language along with the commands. Further, we will learn about the extension.

SQL Extensions

Some effective organizations set official rules for SQL in the 1980s. Two organizations were there, ANSI and ISO, and they agreed on some rules in 1986 and 1987. Moreover, they update these rules every few years. The most recent update was in 2016. Additionally, the official name for these rules is ISO/IEC 9075:2016. In other words, it's a code that everyone follows.

• There are different types of SQL, like Microsoft's SQL Server, Oracle Database, and others.
• They all follow the main rules but might add some extra stuff to stand out.
• Each company adds a bit of its flavor to SQL. For example - Microsoft has Transact-SQL, and Oracle has a Procedural Language for SQL.

Now, we will learn the uses of Structured Query Language.

Benefits of SQL

• You can use SQL on different devices like computers, laptops, and even some phones. 
• No matter how much data there is, SQL can quickly add, remove, find, and organize data. As a result, it makes it easy to share.
• You use words like 'create,' 'insert,' 'select,' and 'update' without being a coding genius.
• SQL uses the English language. In other words, anyone can understand it, even if you haven't done it before.
• SQL lets different people see the same data in different ways.
• There are free versions of SQL, like MySQL and others. Big companies like IBM and Microsoft use it.
• It's interactive and easy to understand. As a result, it reduces confusion between people.

The following section will highlight the most necessary topic of SQL. As a result, it’s all about the Structured Query Language Tool.

SQL Tools

SQL-on-Hadoop is a trick for companies dealing with lots of data stored in Hadoop. It's a unique kind of SQL that contains massive data collections using familiar language. Additionally, it makes it easier for database experts to work there without learning complicated stuff like MapReduce.

There are more than a dozen tools available, either for free or as commercial versions. In short, everyone should pick the right tool for their job. Plus, if you're into Apache Spark (a popular data processing engine), it comes with a bonus feature called Spark SQL. However, it adds even more SQL power to the mix when working alongside Hadoop.

Concluding Words

This SQL structured query language guide is here to help you explore relational databases. Whether you're a developer, analyst, or database administrator, understanding SQL well means you can handle databases smartly. As a result, it makes sure your data stays safe and reliable. Keep in mind that the more you practice with databases and writing SQL queries – the more confident and skilled you get. However, it becomes crucial for managing data effectively.