# Introduction to SQL for Dummies

Welcome to a beginner's guide to SQL! I'm Brahma 👋, a passionate software developer. I am documenting my learning journey through a series of blog posts. Stay tuned!!

## Introduction

*Ahh!! The boring stuff again!! 🥲*

**Brief History and Development**

MySQL is an open-source relational database management system (RDBMS) that has been a cornerstone of database management since its inception in 1995 by Swedish company MySQL AB. It was created by Michael "Monty" Widenius, David Axmark, and Allan Larsson. MySQL was designed to provide a reliable, high-performance database solution that was easy to use and available to everyone.

In 2008, MySQL AB was acquired by Sun Microsystems, which was subsequently acquired by Oracle Corporation in 2010. Under Oracle’s stewardship, MySQL has continued to evolve, maintaining its open-source nature while benefiting from Oracle's extensive resources and expertise.

**Overview of Relational Databases**

Relational databases are a type of database that store data in structured tables, which are organized into rows and columns. Each table represents a collection of related data, and each row in a table corresponds to a unique record, while columns represent the attributes of the data.

The key feature of relational databases is the ability to use Structured Query Language (SQL) to query and manipulate data. SQL is a powerful language that allows for precise data retrieval, updating, and management, making relational databases highly flexible and efficient.

### Installation and Setup

*The not-so-cool part yet the necessary evil!!🫠*

**Windows:**

1. **Download MySQL Installer:** Visit the [MySQL website](https://dev.mysql.com/downloads/installer/) and download the installer for Windows.
    
2. **Run the Installer:** Launch the installer, choose "Developer Default" setup, and follow the prompts.
    
3. **Configuration:** Set a strong root password and configure any additional user accounts.
    
4. **Complete Installation:** Finish the setup. MySQL is now installed.
    

**macOS:**

1. **Download MySQL DMG:** Download the DMG file from the [MySQL website](https://dev.mysql.com/downloads/mysql/).
    
2. **Install MySQL:** Open the DMG file, run the installer, and set the root password during installation.
    
3. **Start MySQL Server:** Start the server from System Preferences or via command line:
    
    ```bash
    sudo /usr/local/mysql/support-files/mysql.server start
    ```
    

**Linux:**

1. **Debian/Ubuntu:**
    
    * Update and install MySQL server:
        
        ```bash
        sudo apt update
        sudo apt install mysql-server
        ```
        
    * Secure the installation:
        
        ```bash
        sudo mysql_secure_installation
        ```
        
2. **RHEL/CentOS:**
    
    * Add the MySQL repository and install MySQL server:
        
        ```bash
        sudo yum localinstall https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
        sudo yum install mysql-server
        ```
        
    * Start and secure the server:
        
        ```bash
        sudo systemctl start mysqld
        sudo mysql_secure_installation
        ```
        

## Running SQL

Just run the SQL Command Line or the WorkBench if you decide to use MySQL. And that's it!!! Good to go!

## Basic Concepts

*The usual jargon!! 😁*

* **Database:** A collection of organized data stored and accessed electronically. Think of it as a filing cabinet where all your information is stored.
    
* **Table:** A structured format within a database that organizes data into rows and columns. It's similar to a single drawer in the filing cabinet, with labeled folders (columns) and sheets of paper (rows).
    
* **Record:** A single entry or row in a table, representing a set of related data. This is akin to a single sheet of paper in a folder, containing all details for a specific item.
    

*Is that anyway related to IRL? - Yes!! It does!! Read on 👉*

* **Database:** Imagine a library. Each bookshelf represents a database, containing a variety of books (tables) on different subjects.
    
* **Table:** Within our library, a specific bookshelf might be dedicated to science books. Each book on this shelf is a table with chapters (columns) and pages (rows).
    
* **Record:** A single page within a science book, which has data like the title, author, and content, represents a record.
    

# SQL Basics

SQL is the language used to interact with databases. It allows you to retrieve, update, insert, and delete data. It's the standard language for relational database management systems.

*Now let's do some actual grind 😁!!*

#### Creating a Database and Tables & Inserting Data

To create a new database and a table in MySQL, you can use the following commands:

1. **Creating a Database:**
    
    ```sql
    CREATE DATABASE mydatabase;
    ```
    
2. **Creating a Table:**
    
    ```sql
    CREATE TABLE users (
        id INT AUTO_INCREMENT PRIMARY KEY,
        name VARCHAR(100),
        email VARCHAR(100),
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    );
    ```
    
3. **Inserting Data**
    
    **Using the INSERT INTO Statement:**
    
    ```sql
    INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com');
    ```
    
    **Inserting Multiple Records:**
    
    ```sql
    INSERT INTO users (name, email) VALUES 
    ('Bob', 'bob@example.com'),
    ('Charlie', 'charlie@example.com'),
    ('Diana', 'diana@example.com');
    ```
    

**Common SQL Commands**

1. **SELECT:** Retrieves data from one or more tables.
    
    ```sql
    SELECT column1, column2 FROM table_name WHERE condition;
    ```
    
    Example:
    
    ```sql
    SELECT name, email FROM users WHERE age > 18;
    ```
    
2. **INSERT:** Adds new records to a table.
    
    ```sql
    INSERT INTO table_name (column1, column2) VALUES (value1, value2);
    ```
    
    Example:
    
    ```sql
    INSERT INTO users (name, email) VALUES ('John Doe', 'john.doe@example.com');
    ```
    
3. **UPDATE:** Modifies existing records in a table.
    
    ```sql
    UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;
    ```
    
    Example:
    
    ```sql
    UPDATE users SET email = 'john.newemail@example.com' WHERE name = 'John Doe';
    ```
    
4. **DELETE:** Removes records from a table.
    
    ```sql
    DELETE FROM table_name WHERE condition;
    ```
    
    Example:
    
    ```sql
    DELETE FROM users WHERE name = 'John Doe';
    ```
    

What you just read is also called **CRUD** operation -> **Create Read Update Delete**.

## Where, Order by & Group by

To make the SELECT clause powerful 💪

*Let's understand the jargon!!!*

**Basic SELECT Queries**

To retrieve data from a table in MySQL, you use the `SELECT` statement. Here are some examples:

```sql
SELECT * FROM users;
```

This retrieves all columns from the `users` table.

```sql
SELECT name, email FROM users;
```

This retrieves only the `name` and `email` columns from the `users` table.

**Filtering Results with WHERE Clauses**

You can filter results based on specific conditions using the `WHERE` clause. Examples:

```sql
SELECT * FROM users WHERE age > 18;
```

This retrieves all records from the `users` table where the `age` column is greater than 18.

```sql
SELECT name, email FROM users WHERE name = 'Alice';
```

This retrieves records from the `users` table where the `name` column is 'Alice'.

**Sorting Results with ORDER BY**

You can sort the results of your query using the `ORDER BY` clause. Examples:

```sql
SELECT * FROM users ORDER BY name ASC;
```

This retrieves all records from the `users` table sorted in ascending order by the `name` column.

```sql
SELECT * FROM users ORDER BY created_at DESC;
```

This retrieves all records from the `users` table sorted in descending order by the `created_at` column.

**Grouping Results with GROUP BY**

The `GROUP BY` clause is used to group rows that have the same values into summary rows. Example:

```sql
SELECT department, COUNT(*) as employee_count FROM employees GROUP BY department;
```

This retrieves the count of employees in each department from the `employees` table, grouped by the `department` column.

# Conclusion

Now I bet you are well equipped to be a SQL Developer on LinkedIn😂.

But jokes aside, this article covers major beginner level jargon. Joins, for those who know, would be covered in a upcoming article coz that deserves one 😂. For those who don't know what is that just stay tuned and subscribe to my newsletter to get updated on that too.

That's all folks. Leave a like and some lovely critics in the comments😁.

Signing off!!!👋