What are SQL Databases - All That You Need to Know!

SQL databases made easy! All your questions about SQL databases answered in one recipe guide by ProjectPro!

Recipe Objective - What are SQL Databases - All That You Need to Know! 

SQL databases are a fundamental component of the modern data-driven world, powering a wide range of applications and systems. They are an essential tool for storing, managing, and retrieving data efficiently. Check out this recipe guide to explore the world of SQL databases, exploring their uses, functionality, types, and much more. Let's begin by understanding the basics.

What are SQL Databases? 

SQL, which stands for Structured Query Language, is a domain-specific language used for managing and manipulating relational databases. A SQL database, or relational database, is a collection of structured data organized into tables with rows and columns. These databases are designed to store, retrieve, and manage data efficiently and reliably.

What Are SQL Databases Used For?

SQL databases are used in a wide variety of applications and industries due to their robust features and capabilities. Some common use cases include:

  • Data Storage: SQL databases serve as a secure and structured repository for data. They are the go-to choice for applications that require organized data storage.

  • Data Retrieval: SQL databases allow for efficient data retrieval using SQL queries. This feature is essential for applications that need to access specific pieces of information quickly.

  • Data Integrity: SQL databases ensure data integrity by enforcing constraints, such as primary keys and foreign keys, which prevent data corruption.

  • Data Analysis: Many business intelligence and reporting tools rely on SQL databases to analyze and generate insights from large datasets.

  • Web Applications: SQL databases are often used as the backend data store for web applications, ensuring data consistency and reliability.

How Do SQL Databases Work?

SQL databases work by organizing data into tables, each containing rows and columns. These tables are interrelated through keys, which establish relationships between data. When you want to retrieve or manipulate data, you use SQL queries to interact with the database. Here's a basic overview of how SQL databases function:

  • Data Storage: Information is stored in tables, each of which represents a specific entity or data type.

  • Data Retrieval: SQL queries are used to extract data from the tables based on specific criteria.

  • Data Modification: SQL allows you to insert, update, or delete data, ensuring that the database remains up to date.

  • Data Relationships: Keys, such as primary keys and foreign keys, establish relationships between tables, enabling complex data structures.

Types of SQL Databases (SQL Databases Examples) 

There are several types of SQL databases, each designed to meet different needs:

  • Relational Databases: These are the most common type and include databases like MySQL, PostgreSQL, and Microsoft SQL Server.

  • Open Source SQL Databases: Examples of open-source SQL databases include MySQL and PostgreSQL. They are freely available and widely used.

  • Cloud SQL Databases: Cloud-based databases like Amazon RDS and Google Cloud SQL provide scalable and managed database solutions in the cloud.

  • Distributed SQL Databases: Distributed databases like Apache Cassandra and CockroachDB are designed to handle massive amounts of data and provide high availability.

  • System Databases in SQL Server: System databases in SQL Server are used for internal purposes, such as storing system metadata.

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How to Interact with SQL Databases? 

Now that you understand the basics, let's explore some common operations when working with SQL databases:

How to Create a Database in SQL?

The first step in storing data in a structured format is to create a database. In both SQL and MySQL, this can be done by using the “CREATE DATABASE” statement.

Syntax: CREATE DATABASE database_name;

Example:
Let's say we want to create a database for company A. We can do this simply by writing the following query –

Code:

CREATE DATABASE CompanyA;

Output:

Query OK, 1 row affected (0.03 sec)

How to List All Databases in MySQL?

If you want to take a look at the names of all the databases that exist in your system, you can do so with the help of the “SHOW DATABASES” statement in MySQL.

Syntax: SHOW DATABASES;

Example:

Code: 

SHOW DATABASES;

Output:

+--------------------+

| Database           |

+--------------------+

| companya           |

| information_schema |

| k                  |

| mysql              |

| performance_schema |

| sakila             |

| student_backup     |

| sys                |

| world              |

+--------------------+

9 rows in set (0.00 sec)

We can see our recently created “companya” database in the list as well.

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How to Rename a Database in SQL? 

You may need to rename a database at some point. This could be because the previous name is no longer applicable, or because the database has to be renamed temporarily.

In SQL you can rename a database using “EXEC” or “ALTER DATABASE” statements.

Syntax:
EXEC sp_renamedb “old_db_name”, “new_db_name”;
ALTER DATABASE old_db_name MODIFY NAME = new_db_name;

Code:

EXEC sp_renamedb "CompanyA","company_a";

ALTER DATABASE company_a MODIFY NAME = CompanyA;

How to Drop a Database in SQL?

Let's say there arises a need to completely drop a database. You can do so using the “DROP DATABASE” statement.

Syntax:
DROP DATABASE database_name;

If you want to drop the database that we just created, you can use the following query –

Code:

DROP DATABASE CompanyA;

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How to Select a Database in SQL?

When your SQL Schema has numerous databases, it is important that you first choose a database where all of your actions will be done before proceeding. You can select a pre-existing database in your SQL Schema with the help of the “USE” statement.

Syntax: USE database_name;

For all further queries, we want to make use of the CompanyA database that we had created initially. To make sure that all of the queries are run in this database we will use the following query –

Code:

USE CompanyA;

SQL vs. NoSQL - Difference Between SQL Databases and NoSQL Databases 

The distinction between SQL and NoSQL databases revolves around data structure, scalability, query language, schema, and transaction properties. SQL databases follow a structured, relational model with predefined schemas and support powerful querying through the SQL language. They prioritize data consistency and are commonly used in applications like financial systems. In contrast, NoSQL databases offer flexibility in data models, excel at horizontal scalability, employ varied query languages, and can adapt to changing schemas. They prioritize high availability and are often used in applications where data evolves rapidly, such as content management systems and real-time analytics platforms. Choosing between SQL and NoSQL databases hinges on the specific requirements of a project, with SQL databases excelling in structured, complex data environments and NoSQL databases catering to scenarios with dynamic data needs and high scalability demands.

Become a SQL Proficient with ProjectPro! 

This recipe has provided a comprehensive overview of what SQL databases are and their vital role in managing and organizing data. However, it's crucial to remember that theoretical knowledge alone is not sufficient in today's competitive job market. Practical experience is the key to mastering SQL and related skills. This is where ProjectPro comes into play, offering a rich repository of over 270 solved projects in the field of data science and big data. With guided video explanations and readily available source codes, ProjectPro equips learners with the hands-on experience they need to enhance their SQL skills and stay ahead in the dynamic field of data management and analysis. So, don't just stop at knowing what SQL databases are – take the leap into the practical world with ProjectPro and unlock a world of opportunities in the data-driven industry.

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