sqlzoo.net

Yes, but only as supplementary reference material. SQLZoo's main learning path is a step-by-step SQL tutorial using browser-based practice tables. The "Reference: how to..." section adds a small set of pages on using SQL from application code and cloud servers: SQL with PHP on Amazon EC2, connecting to a database with C#, and an introduction to transactions. These are not part of the numbered tutorial sequence and are not required to learn SQL on the site.

What the reference section actually contains

The SQLZoo reference index lists these application-oriented entries alongside core syntax topics like SELECT, CREATE/DROP, INSERT/DELETE, dates, functions, users, and metadata:

So the cloud-server coverage is specifically PHP + MySQL + Apache on EC2, and the C# coverage is a code sample for database connection. Neither is a full course in those languages or platforms.

How this fits into SQLZoo overall

SQLZoo organizes its content into four groups, per the site's own headings:

• Tutorials — the numbered step-by-step path (0 SELECT basics through 12 DDL), each built around a practice table such as World, Nobel, or the Movie Database.
• Reference — "how to" pages, including the PHP/EC2, C#, and transactions items above.
• Assessments — more involved examples for confident users.
• Challenges — additional exercises.

The application and cloud pages sit in Reference, which means they are look-up material rather than guided lessons. If your goal is to learn SQL syntax and querying, the numbered tutorials are the relevant path; the PHP, C#, and transactions pages become useful once you already write queries and need to run them from an application or understand concurrent sessions.

When these pages are worth your time

• You are setting up a LAMP-style stack on EC2. The PHP/EC2 videos and the Napier module instructions are aimed at getting MySQL, PHP, and Apache running together on Amazon's cloud servers.
• You need a starting snippet for C#. The C# page provides connection code rather than a tutorial, so expect a reference example, not a walkthrough.
• You want to understand why concurrent sessions conflict. The transactions videos demonstrate session interference and how to prevent it — useful background before working with multi-user applications.

If none of these match your situation, you can skip the section entirely; nothing in the main tutorial sequence depends on it.

Practical caveat

The reference index describes these as video tutorials and code samples, but it does not state versions, prerequisites, or how current the EC2 and C# material is. Treat them as starting points and check the specific tooling versions you plan to use against current documentation before relying on the setup steps.

If you're new to Ahrefs and want to run your first SEO audit, the fastest path is: open Site Explorer, enter your target URL, review the Overview for a health snapshot, then dig into Organic Keywords, Top Pages, and Site Audit to find specific problems. From there, build a short prioritized to-do list instead of trying to fix everything at once.

This tutorial walks through that workflow using a realistic starting scenario, explains what the numbers mean, and shows how to turn findings into actions.

Before You Start: Pick a Narrow Scope

A common beginner mistake is auditing an entire large website on day one. The reports become overwhelming, and you can't tell which issues matter.

Instead, choose one of these starting points:

• A single important page (your homepage or a key product/service page)
• A small site (under ~50 pages, e.g., a personal blog or small business site)
• One section of a bigger site (e.g., /blog/)

For this tutorial, assume you're auditing a small business site with about 30 pages. The same steps scale up later.

You'll need an Ahrefs account to follow along. Ahrefs offers paid plans, and pricing and feature limits change over time, so check the current Pricing page for what's included in each tier before committing.

Step 1: Enter Your Target in Site Explorer

Site Explorer is Ahrefs' core tool for analyzing any website or URL.

1. Open Site Explorer from the top navigation.
2. In the search box, paste your domain (e.g., example.com).
3. Choose the Exact URL or Domain mode depending on scope. For a full-site view, use Domain or Prefix; for a single page, use Exact URL.
4. Press Enter.

You'll land on the Overview report. Don't try to absorb everything — focus on four numbers first.

Reading the Overview Snapshot

Important caveat: Ahrefs' traffic and keyword numbers are estimates based on its own data. They won't match Google Search Console or your analytics exactly. Treat them as directional, not absolute.

Step 2: See What You Already Rank For

Go to Organic Keywords in the left sidebar. This shows queries where your site appears in search results.

Sort by Traffic (descending) to see which pages bring the most estimated visitors. Then look for:

• Keywords ranking in positions 4–15 — these are often the easiest wins. A small content or on-page improvement can push them onto page one.
• Keywords with high volume but low position — potential opportunities if the topic is relevant.
• Irrelevant keywords — if you rank for something off-topic, it may signal thin or mismatched content.

Write down 5–10 of the position 4–15 keywords. These become your first optimization targets.

Step 3: Find Your Best and Weakest Pages

Open Top Pages. This ranks your URLs by estimated organic traffic.

Look for two things:

1. Your top performers — understand what topics and formats work. Can you create more content like this?
2. Pages with traffic but poor rankings — these may need on-page fixes (title, headings, internal links).

If a page gets zero traffic and targets a topic you care about, it's a candidate for a rewrite or consolidation.

Step 4: Run a Technical Site Audit

Now move to Site Audit. This crawls your site and flags technical and on-page issues.

1. Click Site Audit → New project.
2. Enter your domain and set crawl settings (default is usually fine for a small site).
3. Start the crawl and wait for it to finish.

Once complete, you'll see a Health Score and a list of issues grouped by category.

Which Issues to Fix First

Not all issues are equal. Prioritize in this order:

Ignore low-impact warnings (like minor meta description length) until the big items are handled.

Step 5: Turn Findings Into a To-Do List

You now have raw data. Convert it into a short, actionable list. Example:

1. Fix 3 broken links found in Site Audit.
2. Rewrite title tags on 5 pages with duplicate titles.
3. Improve 4 pages ranking in positions 6–12 by adding missing subtopics and internal links.
4. Remove or update 2 thin pages with no traffic.

Keep the list to 5–10 items max for your first audit. Finishing a short list beats starting a long one.

Common Beginner Mistakes

• Chasing every red flag. Site Audit flags many minor issues. Fix what affects rankings and users first.
• Trusting estimates as exact numbers. Ahrefs data is modeled, not measured from your analytics.
• Auditing a huge site too early. Start small to learn the interface.
• Ignoring search intent. A page can be technically perfect but still fail if it doesn't match what searchers want.
• Forgetting to re-crawl. After fixes, run Site Audit again to confirm improvements.

Where to Go Next

Once your first audit is done:

• Compare with competitors using Site Explorer's Competing Domains and Content Gap reports.
• Track keyword rankings over time with Rank Tracker.
• Explore backlink opportunities in the Backlinks and Link Intersect reports.
• Set up recurring Site Audit crawls so new issues surface automatically.

Your first audit isn't about perfection — it's about building a repeatable habit: enter a target, read the key reports, pick the highest-impact fixes, and act. Do that once a month and your site's health compounds.

Start with 0 SELECT basics, then work through 1 SELECT name and 2 SELECT from World in order. SQLZoo organizes its tutorials as a numbered sequence that moves from simple SELECT queries to joins, aggregates, window functions, and finally database creation and DDL. The numbering is the intended path: each tutorial builds on the tables and query patterns introduced earlier, so skipping ahead usually means meeting syntax you haven't practiced yet.

The tutorial sequence at a glance

SQLZoo's main "Learn SQL step by step" track runs from 0 to 12, with a few extra numbered topics inserted along the way:

Each tutorial is built around a specific example table — country profiles, Nobel winners, World Cup matches, movies, teachers and departments, election results, bus routes. That design means you learn a concept by querying real-shaped data rather than abstract syntax.

Where a beginner should start

The first three steps are the on-ramp:

1. 0 SELECT basics — the simplest queries, enough to understand how to read rows from a table.
2. 1 SELECT name — pattern matching, so you learn to filter with conditions rather than just display everything.
3. 2 SELECT from World — the first substantial table, where basic features get combined.

Only after those should you move to 3 SELECT from Nobel (extra practice on the same basics) and 4 SELECT within SELECT (subqueries). Steps 0–3 are all about SELECT; the course deliberately delays aggregates and joins until step 5 and 6.

A practical checkpoint: if you can write a query on the World table that filters rows and returns selected columns without looking anything up, you're ready for step 4.

After the basics: the intermediate and advanced track

• 5 SUM and COUNT introduces aggregate functions.
• 6 JOIN and 7 More JOIN operations are the two join tutorials, using different datasets (World Cup and a movie database), so you see joins applied twice before moving on.
• 8 Using Null covers missing values, and 8+ Numeric Examples adds more complex calculations.
• 9- Window function, 9+ COVID 19, and 9 Self join are the advanced querying topics; the self join tutorial uses Edinburgh bus routes joined to themselves.
• 10 Tutorial Quizzes lets you test knowledge with multiple-choice quizzes before the database-building material.

Beyond the step-by-step track

SQLZoo also lists two other sections alongside the numbered tutorials:

• Reference: how to... — task-oriented guides covering SELECT, CREATE and DROP, INSERT and DELETE, DATE and TIME, functions, users and permissions, meta data, SQL hacks, transactions, and using SQL with PHP on Amazon EC2 or with C#. Use these when you need to look up a specific operation rather than follow a lesson.
• Assessments — more involved examples for confident users, plus Challenges.

The site also offers language options (English, 日本語, русский, 中文) and notes that you can log in, though the tutorial pages themselves are readable without an account.

A suggested route

For a beginner, the shortest sensible path is 0 → 1 → 2 → 3 → 4 → 5 → 6 → 7, pausing at 10 Tutorial Quizzes to check retention, then continuing to 8, 8+, 9-, 9+, 9 for nulls, numeric work, window functions, and self joins. Leave 11 Student Records and 12 DDL until you want to create and import your own data, and dip into the Reference section whenever a tutorial assumes a command you haven't met.

SQLZoo's reference section is a set of "how to..." guides covering nine numbered topics plus two application-focused entries: reading data with SELECT, creating and dropping objects, inserting and deleting records, working with dates and times, using functions, managing users and permissions, querying metadata, SQL Hacks, and an introduction to transactions, followed by guides on using SQL with PHP on Amazon EC2 and with C#. It is a lookup resource for syntax and technique rather than a step-by-step course — the numbered tutorials (0–12) are where you learn by doing.

The reference topics at a glance

How the reference fits with the rest of SQLZoo

The site splits its material into three layers, and knowing which one you need saves time:

• Tutorials (0–12) — the step-by-step learning path, from SELECT basics through joins, NULL handling, window functions, COVID-19 data, self joins, quizzes, student records and DDL/import instructions.
• Reference — the "how to..." pages above. Use these when you know what you want to do but need the syntax or the exact clause.
• Assessments and Challenges — more involved examples for confident users, plus multiple-choice tutorial quizzes.

A practical pattern: work a tutorial chapter, then jump to the matching reference page when a clause doesn't behave as expected. For example, after the SUM and COUNT tutorial, the Functions reference is where you check which string, logical or mathematical functions are available.

What the reference does not cover

The reference pages are organised around tasks, not around a formal syllabus. Topics such as subqueries, joins and window functions appear in the tutorial track (chapters 4, 6–7 and 9- respectively) rather than as standalone reference entries. If you are looking for a structured sequence, start with the tutorials; if you are looking for a specific operation, the reference list above is the index.

The site displays an "Anonymous / Not logged in / Log in" state, so some progress-related features may depend on an account, but the reference content itself is presented as part of the public tutorial pages.

SQLZoo is a free, browser-based SQL learning site. You use it to practice SQL directly against real datasets, working through numbered tutorials that start at SELECT basics and move up to joins, window functions, and self joins. You can start without an account; the site shows an "Anonymous / Not logged in" state with a login option. Use it if you want hands-on query practice rather than video lectures, and if you're comfortable reading short written instructions in English (the site also lists Japanese, Russian, and Chinese language links).

What SQLZoo contains

The site organizes its material into four sections, each with a distinct purpose.

Tutorials: Learn SQL step by step

This is the core of the site — a numbered sequence of interactive lessons, each built around a specific table so you write queries against real data rather than abstract examples.

The progression matters: step 4 (subqueries) assumes you can already filter rows from step 2, and step 7 (joining actors to movies) assumes the join logic from step 6. Skipping ahead tends to produce queries that run but return the wrong rows, because you won't yet know how the tables relate.

Reference: how to...

A lookup section for syntax and operations you'll need outside the guided lessons:

• SELECT — reading data from a database
• CREATE and DROP — creating and removing tables, indexes, and views
• INSERT and DELETE — adding, changing, and removing records
• DATE and TIME — working with dates, including adding, subtracting, and formatting
• Functions — string, logical, and mathematical functions
• Users — creating users, granting and denying access, inspecting and killing processes
• Meta Data — finding which tables and columns exist, counting and limiting returned rows
• SQL Hacks — techniques drawn from the O'Reilly book SQL Hacks
• Using SQL with PHP on Amazon EC2 — video tutorials for running MySQL, PHP, and Apache on EC2, with simpler instructions aimed at students on module INF08104 at Edinburgh Napier University
• An introduction to transactions — video tutorials on how sessions interfere with each other and how to prevent it
• Using SQL with C# — code for connecting to a database

Assessments and Challenges

The site separates "more involved examples for confident users" (assessments) from challenges. These are for testing yourself after the tutorials, not for first learning — attempt them once you can write a join and a subquery without looking anything up.

How to get started

1. Open sqlzoo.net in a browser. No login is required to begin.
2. Start at tutorial 0 (SELECT basics) and work in numerical order. Each tutorial page presents a task, an input area for your query, and the result of running it.
3. When a query returns unexpected output, check the table structure first — the reference section's Meta Data page explains how to list tables and columns.
4. After finishing the tutorials, use the quizzes (step 10) to check retention, then the assessments and challenges for harder problems.

Expected result: by the end of the tutorial sequence you should be able to write queries that filter, aggregate, join multiple tables, use subqueries, handle nulls, and apply window functions — all against datasets you can inspect.

Common sticking points

• Table names and columns differ per tutorial. The World, Nobel, and Movie Database tables have different schemas; read the description on each tutorial page before writing a query.
• JOIN steps are where most learners stall. If step 6 output looks like duplicated or missing rows, the join condition is usually wrong rather than the SELECT list.
• NULL handling is counterintuitive. Step 8 exists precisely because comparisons with NULL don't behave like ordinary values; don't assume = works there.
• The reference section is not a course. It's organized by operation, not difficulty, so use it to look things up rather than to learn sequentially.

When SQLZoo is the right choice

Choose SQLZoo if you want free, interactive practice with immediate feedback and a clear difficulty ladder, and you're learning standard SQL syntax for querying. It suits self-directed learners and students supplementing a course. It is less suited to you if you need structured video instruction, certification, or training in a specific vendor's dialect beyond what the tutorials cover — the site's own material is oriented toward MySQL in its DDL and PHP sections, and its transaction and C# pages are video- and code-based supplements rather than full courses.