A Beginner’s Guide To SQL

Ouija
3 min readMar 12, 2023

SQL (Structured Query Language) is a programming language used to communicate with relational databases. It allows you to create, modify, and retrieve data stored in a database.

Getting started

To begin coding in SQL, you need to have access to a database management system (DBMS) that supports SQL. Examples of popular DBMSs include MySQL, Oracle, SQL Server, and PostgreSQL. You can download and install these on your local machine, or use an online service that provides access to a DBMS.

Creating a database

Once you have access to a DBMS, you can create a new database. To do this, you use the CREATE DATABASE statement, followed by the name of the database:

CREATE DATABASE mydatabase;

This statement creates a new database called “mydatabase”.

Creating a table

After creating a database, you can create one or more tables to store data. A table is a collection of related data organized into rows and columns. To create a new table, you use the CREATE TABLE statement, followed by the name of the table and a list of columns:

CREATE TABLE customers (
id INT PRIMARY KEY,
name VARCHAR(50),
email VARCHAR(50)
);

This statement creates a new table called “customers” with three columns: “id”, “name”, and “email”. The “id” column is defined as the primary key, which means it will be used to uniquely identify each row in the table.

Inserting data into a table

After creating a table, you can insert data into it using the INSERT INTO statement. Here’s an example:

INSERT INTO customers (id, name, email) VALUES (1, 'Chad', 'chad@example.com');

This statement inserts a new row into the “customers” table with the values “1”, “Chad”, and “chad@example.com” in the “id”, “name”, and “email” columns, respectively.

Retrieving data from a table

To retrieve data from a table, you use the SELECT statement. Here’s an example:

SELECT * FROM customers;

This statement retrieves all rows and columns from the “customers” table.

Updating data in a table

To update data in a table, you use the UPDATE statement. Here’s an example:

UPDATE customers SET email = 'chad@example.com' WHERE id = 1;

This statement updates the “email” column of the row in the “customers” table with an “id” of “1” to “chad@example.com”.

Deleting data from a table

To delete data from a table, you use the DELETE statement. Here’s an example:

DELETE FROM customers WHERE id = 1;

This statement deletes the row in the “customers” table with an “id” of “1”.

These are just a few basic SQL commands to get you started. SQL has many more features and capabilities, so there’s a lot more to learn if you want to become proficient in it.

I strongly advise you head on over to https://dune.com/ and experiment!

Written by myself, @0xOuija

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Ouija

I am a researcher focused on philosophy, heuristics, decentralisation, DAOs and DeFi. Believe in the sovereignty of the individual for all.