The internet is built on data. Every second, quintillions of bytes are created, but this massive volume of information needs a home. The answer? Databases.
A database is a systematic collection of data stored and retrieved electronically. To access this data, professionals use SQL (Structured Query Language). If you are new to data, this article is your roadmap.
We will cover what SQL is, the essential commands you need to know to get started, and how it powers modern industries.
What is SQL?
SQL (Structured Query Language) is the standard programming language used to manage relational databases. It allows you to communicate with the database to perform tasks like retrieving, updating, or deleting specific data.
Standardized by ANSI in 1986 and ISO shortly after, SQL remains the backbone of data management. It is the primary language used by top Relational Database Management Systems (RDBMS), including:
- Microsoft SQL Server
- Oracle
- Access
- Sybase
- Ingres
SQL Quick Reference Guide
Before we dive into the details, here is a quick reference table of the commands every beginner should know. This covers the vast majority of daily SQL tasks.
| Command | Function | Category |
|---|---|---|
| SELECT | Retrieves data from a database. | DQL (Query) |
| CREATE | Creates a new database or table. | DDL (Definition) |
| INSERT INTO | Inserts new data into a table. | DML (Manipulation) |
| UPDATE | Modifies existing data in a table. | DML (Manipulation) |
| DELETE / TRUNCATE | Removes data from a table. | DML (Manipulation) |
Top SQL Commands (With Syntax & Examples)
Let’s look at how these commands are written in practice.
1. Create
The CREATE command is used to build a new database, table, or view.
Creating a Database
CREATE DATABASE DatabaseName;Creating a Table
To create a table, you must define the columns and the data type for each column (e.g., integer, varchar).
CREATE TABLE Employee
(
CustomerID int,
CustomerName varchar(255),
PhoneNumber int,
City varchar(255)
);2. Insert Into
Once your table is built, you need to populate it. Use the INSERT INTO statement to add new rows.
INSERT INTO Employee (CustomerID, CustomerName, PhoneNumber, City)
VALUES ('15', 'Ana', '5550199', 'London');3. Select
This is the most common command. It fetches data from the database.
To select specific columns:
SELECT EmployeeID, EmployeeName FROM Customers;To select everything (all columns) in a table:
SELECT * FROM Employee;4. Update
Use this to modify existing records. Note: Always use a WHERE clause, otherwise you will update every single row in the table.
UPDATE Employee
SET City = 'Los Angeles'
WHERE EmployeeID = 5;5. Delete & Truncate
There are two ways to remove data:
- DELETE: Removes specific rows based on a condition (can be rolled back in some systems).
- TRUNCATE: Wipes all data from the table instantly (cannot be rolled back).
/* Removes only customer 5 */
DELETE FROM Customers WHERE CustomerID = 5;
/* Wipes the entire table clean */
TRUNCATE TABLE Customers;6. Alter
Use ALTER to change the structure of the table itself, such as adding or deleting a column.
ALTER TABLE Employee ADD Address varchar(255);7. Drop
This is the "nuclear option." DROP deletes the entire table or database permanently.
DROP TABLE Employee;Why use SQL? (Advantages)
Why has SQL remained the standard for over 40 years? It solves the major problems of older file systems: redundancy, security risks, and slow retrieval speeds.
Key Advantages:
- Universal: It is portable. The query you write for one system often works on another with minor tweaks.
- High Speed: It can retrieve massive amounts of data in milliseconds.
- No Coding Experience Required: SQL uses English-based syntax (e.g., "Select," "Where," "From"), making it one of the easiest languages for beginners to learn.
Related: 10 Best Online SQL Courses for Beginners
Industries That Use SQL
SQL is industry-agnostic. If a company has data, they likely use SQL.
- Finance: For managing assets, transactions, and fraud detection in real-time.
- Healthcare: For maintaining secure patient records, pharmacy databases, and staff assignments.
- Retail: For inventory management and analyzing customer purchasing behavior.
- Education: For tracking syllabus, attendance, student grades, and fee processing.
A Brief History of SQL
SQL was originally developed in the 1970s by IBM researchers Raymond Boyce and Donald Chamberlin. It was initially called SEQUEL (Structured English Query Language). The concept was based on a paper by Edgar Frank Codd regarding the relational model of data.
In 1979, Relational Software (now Oracle) released the first commercial version. Today, it is the international standard for database communication.
Conclusion
SQL is the bridge between raw data and actionable insights. Whether you are a marketer, a developer, or a business analyst, learning these basic commands allows you to handle large volumes of information with ease.
Ready to move past the basics and master the language?
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