To get started with SQL, open a database and its client, create a small table, insert a few rows, and retrieve them with SELECT. These five steps use PostgreSQL and its psql client so every command follows one dialect. If you use MySQL, SQLite, or another system, setup steps and some SQL features may differ.
1. Choose a database and open a practice database
SQL is the language you use to work with data; a database system stores and manages that data, and a client gives you somewhere to run SQL statements. This guide uses PostgreSQL. Its introductory tutorial walks through installation, creating a database, and connecting to it before moving on to SQL: PostgreSQL: Getting Started.
Install PostgreSQL using the instructions for your operating system and version, then create or select a practice database and start psql, PostgreSQL’s interactive terminal. Once connected, you can enter statements at its prompt. The precise installation and connection commands depend on your operating system and setup, so follow the official instructions for your environment rather than assuming one command works everywhere.
2. Understand tables, rows, columns, and data types
A relational database organizes information in tables. Each table has named columns, and each column has a data type that describes the values it can hold. Each row is one record. For a simple reading list, a books table could have an integer identifier, a text title, and a text author.
Free tools Windows power users keep installed
One-click scans. No signup required.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
PostgreSQL’s tutorial introduces these concepts before using them in table definitions. SQL implementations are not identical: PostgreSQL notes that some of its language features are extensions to the SQL standard. Keeping this example in PostgreSQL avoids mixing dialects; consult your database’s documentation when adapting it. See the PostgreSQL 17 tutorial.
3. Create a table and add a few rows
At the psql prompt, create the table with CREATE TABLE, then add records with INSERT:
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
CREATE TABLE books (
id INTEGER,
title TEXT,
author TEXT
);
INSERT INTO books (id, title, author)
VALUES
(1, 'The Left Hand of Darkness', 'Ursula K. Le Guin'),
(2, 'Kindred', 'Octavia E. Butler'),
(3, 'Piranesi', 'Susanna Clarke');CREATE TABLE defines the columns and their types; INSERT supplies values for those columns. PostgreSQL should acknowledge the table creation and report that three rows were inserted. A table definition can also include constraints, such as requiring an identifier to be unique, but this first example keeps the structure simple.
4. Retrieve and narrow results with SELECT and WHERE
SELECT retrieves data from a table. Name the columns you want to see, then use FROM to specify the table:
Recommended Free Tools
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
SELECT title, author
FROM books;To return only rows that match a condition, add WHERE. For example, this query finds books by one author:
SELECT title, author
FROM books
WHERE author = 'Octavia E. Butler';The result contains Kindred and its author. To request a predictable order, add ORDER BY:
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
SELECT title, author
FROM books
ORDER BY title;SELECT * returns every column and can be handy while exploring an unfamiliar table. Explicitly naming columns makes it clearer which information a query requests. PostgreSQL’s Querying a Table guide covers selecting, filtering, and ordering rows.
5. Practice, then build on the basics
Make the example your own: insert another book, change the author in the WHERE condition, or sort by author instead of title. Then develop the skills that answer broader questions about your data:
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
- Joins combine related data from multiple tables.
- Aggregates, such as counts, summarize rows.
- Updates change existing values.
- Deletions remove rows.
Take particular care with UPDATE and DELETE: a statement without an appropriate WHERE condition can affect every row in the table. Before changing data, run a SELECT with the intended condition to confirm which rows match, then use that condition in the modifying statement.
For a structured alternative to documentation, O’Reilly lists Alan Beaulieu’s Learning SQL, 3rd Edition as beginner-level and covers topics including table design, inserting and modifying data, and query conditions. Its examples are MySQL-oriented, so readers practicing with PostgreSQL should expect dialect differences.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
