SQL: The Language of Relational Databases
Tags: sql, database, computerscience
Published: 2023-02-18 10:00:00

SQL (Structured Query Language) is the standard language for managing and manipulating relational databases. It is used to insert, update, and query data in relational databases, making it an essential tool for anyone working with data. In this article, we'll explore the basics of SQL and how it is used in the real world.

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## **What is SQL?**

SQL is a programming language that is used to manage and manipulate relational databases. It is based on the relational model, which represents data as a series of tables, with each table containing rows and columns. SQL is used to insert, update, and query data in relational databases.

## **SQL commands**

SQL commands are used to interact with relational databases. Some of the most commonly used SQL commands include:

- **SELECT**: Used to retrieve data from a database.
- **INSERT**: Used to add new data to a database.
- **UPDATE**: Used to modify existing data in a database.
- **DELETE**: Used to delete data from a database.
- **CREATE**: Used to create a new table or database.
- **ALTER**: Used to modify the structure of a table or database.

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Here is an example of how to select information and join two tables, one called Orders and another called Customers using SQL:

```sql
SELECT *
FROM orders
JOIN customers
ON orders.customer_id = customers.customer_id;
```

In this example, the **`SELECT`** statement is used to retrieve all columns from the **`orders`** table. The **`JOIN`** clause is used to join the **`orders`** table with the **`customers`** table on the **`customer_id`** column. This query will retrieve all the rows from both tables where the **`customer_id`** column matches in both tables.

It's important to note that the above query will return duplicate columns if both tables have columns with the same name, so it's a good practice to specify the columns you want to select or use the **`AS`** keyword to give the columns a different name in the result set.

Also, this is just a simple example, in real world scenarios, you may want to filter the results using a **`WHERE`** clause or sort the results using an **`ORDER BY`** clause, and many other options depending on the specific needs of your query.

## **SQL in the Real World**

SQL is used in a wide variety of applications, including:

- **Business Intelligence**: SQL is used to extract data from databases and create reports for business intelligence and decision making.
- **Data Warehousing**: SQL is used to manage and query large data warehouses that store historical business data.
- **Web Development**: SQL is used to interact with databases in web applications, such as online stores or social media platforms.
- **Data Science**: SQL is used to extract data from databases for analysis in data science and machine learning.

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SQL is the standard language for managing and manipulating relational databases. It is used to insert, update, and query data in relational databases, making it an essential tool for anyone working with data. With the increasing volume and complexity of data, the importance of SQL will continue to grow in the future. It is widely used in a variety of applications such as Business Intelligence, Data Warehousing, Web Development and Data Science. It's a valuable skill to have for anyone working with data.