Development

In the previous article, you learned how to read data with SELECT. But a database is not useful if you cannot add, change, or remove data. This article covers the three commands that modify data: INSERT, UPDATE, and DELETE. You will also learn about transactions — a way to make sure your changes are safe. Our Sample Database We continue with the same online bookstore database. If you need to set it up, copy the CREATE TABLE and INSERT statements from the first article. ...

You have data. You need to get answers from it. SQL is the language that does this. Every app you use — social media, banking, shopping — stores data in a database. SQL is how developers read, filter, and organize that data. It has been around since the 1970s, and it is still the most important skill for working with data. What Is SQL? SQL stands for Structured Query Language. It is a language for talking to databases. You write a query, and the database gives you the answer. ...

In the previous tutorials, we learned how to build images, run containers, use Compose, and manage volumes and networks. Everything so far happened on your local computer. Now it is time to deploy. In this tutorial, you will learn how to move your application from your laptop to a production server. The Deployment Workflow Deploying with Docker follows a simple pattern: Build the image on your computer (or in CI/CD) Push the image to a registry Pull the image on the server Run the container on the server Your Computer Registry Server ┌──────────┐ ┌──────────────┐ ┌──────────┐ │ Build │────►│ Docker Hub │────►│ Pull │ │ Image │push │ or ghcr.io │pull │ & Run │ └──────────┘ └──────────────┘ └──────────┘ Docker Hub — The Default Registry Docker Hub is the default place to store and share images. It is free for public images and offers one private repository on the free plan. ...

In the previous tutorial, we used Docker Compose to run an app with a database. We briefly mentioned volumes and networking. Now let’s understand them properly. These two topics answer two important questions: Volumes: How do I keep data when a container is removed? Networking: How do containers talk to each other? Why Containers Lose Data Containers are designed to be temporary. You can create them, destroy them, and replace them. This is a feature, not a bug — it makes containers predictable and easy to deploy. ...

In the previous tutorial, we learned how to build a Docker image for a single application. But most real applications need more than one service. A web app might need a database. An API might need a cache. A backend might need a message queue. Running each service with docker run and connecting them manually is tedious. Docker Compose solves this. It lets you define all your services in one file and start everything with a single command. ...

In the previous tutorial, we ran containers from pre-built images like ubuntu and nginx. That is useful, but in real projects you need to package your own application into an image. That is what a Dockerfile does. A Dockerfile is a text file with instructions that tell Docker how to build an image. Think of it as a recipe — each line is a step. Your First Dockerfile Let’s create a simple Node.js application and package it with Docker. ...

You write an app. It works on your computer. You send it to a friend. It does not work on their computer. They have a different operating system, a different version of Python, or missing libraries. This is the classic “it works on my machine” problem. Docker solves it. What Is Docker? Docker is a tool that packages your application and everything it needs into a container. A container includes your code, libraries, system tools, and settings. It runs the same way everywhere — on your laptop, your colleague’s laptop, or a server in the cloud. ...

In the previous tutorial, we learned to work with GitHub and set up CI/CD. Now it is time for the advanced tools. Every developer makes mistakes. You commit the wrong file. You break something and need to find out which commit caused it. You need to grab a single commit from another branch. Git has tools for all of this. In this tutorial, you will learn to undo mistakes, recover lost work, and use power features that save hours of debugging. ...

In the previous tutorial, we learned to merge and rebase branches. But everything happened on your local computer. Real projects involve multiple people working together. This is where GitHub comes in. GitHub is a platform that hosts Git repositories online. It lets you share code, review changes, and automate testing. In this tutorial, you will learn to push code to GitHub, create pull requests, and set up basic CI/CD with GitHub Actions. ...

In the previous tutorial, we learned to create branches and work on them. But branches are only useful if you can bring the work back together. Git gives you two ways to combine branches: merge and rebase. In this tutorial, you will learn both, understand the difference, and know when to use each one. We will also cover merge conflicts and git stash. What Is Merging? Merging takes two branches and combines them. You switch to the branch you want to update, then merge the other branch into it. ...