SQL

TL;DR

Language for creating, modifying, and querying relational databases.
Common operations include retrieving, inserting, updating, deleting, and creating tables.
Widely used across industries such as finance, healthcare, and e-commerce.

Definition

SQL, or Structured Query Language, is a programming language designed specifically for managing and manipulating data stored in relational database management systems (RDBMS).

Explanation

SQL is used to create, modify, and query databases. It provides statements for retrieving data (for example, SELECT), inserting new rows (INSERT), updating existing data, deleting data, and creating new tables. SQL is a versatile tool commonly used in applications across finance, healthcare, and e-commerce, and is essential for working with data in a relational database.

Examples

Example 1: Retrieving data from a database

Suppose you have a database of customer information, including each customer’s name, address, and phone number. To retrieve this data using SQL, you could use the following SELECT statement:

SELECT name, address, phone

FROM customers

This statement would retrieve all of the data from the “customers” table, including the name, address, and phone number for each customer. You can also use the WHERE clause to specify specific criteria for the data you want to retrieve. For example, if you only wanted to retrieve the data for customers who live in a specific city, you could use the following statement:

SELECT name, address, phone

FROM customers

WHERE city = 'New York'

This statement would retrieve only the data for customers who live in New York.

Example 2: Inserting data into a database

Suppose you want to add a new customer to the “customers” table in your database. To do this using SQL, you could use the following INSERT statement:

INSERT INTO customers (name, address, phone)

VALUES ('John Smith', '123 Main St', '555-555-1212')

This statement would add a new row to the “customers” table, with the values ‘John Smith’, ‘123 Main St’, and ‘555-555-1212’ for the name, address, and phone columns, respectively.

These are just a couple of examples of the many things you can do with SQL. Other common operations include updating existing data in a database, deleting data from a database, and creating new tables in a database. SQL is a powerful and versatile language that is essential for working with data in a relational database.

Use cases

Finance
Healthcare
E-commerce

Relational Database Management System (RDBMS)

SQL