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The web is brimming with assets for studying SQL. Most of them, in fact, require paying for data. These assets additionally primarily train you primary or, at finest, intermediate SQL.
The query is, how to learn SQL and do it without cost. Are there any assets in any respect that can train you superior SQL with out paying?
Sure, there are. In truth, there are at the very least 5, as I found.
Earlier than in search of the programs, I needed to outline what superior SQL means.
What’s Superior SQL?
It’s not straightforward to pin this down, as totally different specialists have totally different views (and educating expertise) on which SQL ideas may be thought of superior.
Nonetheless, I believe it’s protected to say that these subjects are superior SQL:
- JOINs
- CTEs
- Recursive CTEs
- Subqueries and Correlated Subqueries
- Window Capabilities
- Pivoting and Unpivoting Knowledge
- Hierarchical Queries
- Views
- Saved & Consumer-Outlined Procedures and Capabilities
- Triggers
- Non permanent Tables
- Indexes
- Knowledge Normalization
- Efficiency Optimization
The listing is incomplete, nonetheless. Another subjects that additionally belong to superior SQL may be added. How are you going to say in the event that they’re superior? I’ve a extremely unscientific however environment friendly methodology: should you don’t know what a specific matter means, it’s most certainly superior SQL.
Free Sources for Superior SQL
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The assets I listing right here cowl some or many of the superior SQL ideas I discussed earlier. If you happen to mix these assets, your superior SQL data can develop into much more healthful. Sure, I do know it requires a bit extra effort, however hey, these are all free. What did you anticipate?
1. Mode SQL Tutorial
Hyperlink to useful resource: Mode Analytics SQL Tutorial
Description: This tutorial teaches you superior SQL within the Mode BI instrument. No want to fret that you just’ll should study yet one more SQL taste; Mode makes use of commonplace SQL.
All of the ideas are defined theoretically intimately. In every lesson, there are additionally interactive workouts the place you possibly can follow fixing issues by writing SQL queries and examine the solutions.
Talking of ideas, you’ll find out about subqueries, window capabilities, tuning SQL queries, and pivoting knowledge. As well as, there are classes about knowledge sorts, date codecs, and string capabilities.
If you happen to really feel you’re combating a few of the much less superior subjects in these classes, you possibly can at all times revisit them within the Fundamental SQL and Intermediate SQL sections of the tutorial.
2. StanfordOnline: Databases: Superior Subjects in SQL
Hyperlink to useful resource: edX
Description: This course is considered one of 5 programs on databases supplied by Stanford College and hosted by edX.
Of the superior subjects, you’ll be taught indexing to enhance question efficiency, transactions, database constraints and triggers, and views.
It’ll take you two weeks to finish the course, with 8-10 hours per week.
As well as, you possibly can take programs on OLAP and recursion, modeling and theory, and semistructured data should you’re enthusiastic about these subjects.
3. Kaggle Superior SQL
Hyperlink to useful resource: Kaggle Advanced SQL
Description: Kaggle’s cute little course will take solely 4 hours to finish. It covers JOINs and UNIONs, analytic (or window) capabilities, nested and repeated knowledge, and recommendations on writing environment friendly queries.
Every lesson supplies detailed theoretical explanations complemented by sensible examples. On the finish of every lesson, you will see a hyperlink to a piece that exams your understanding by providing you with a number of workouts to resolve by writing code.
4. Superior SQL (Summer time 2020)
Hyperlink to useful resource: YouTube
Description: This video course consists of lectures by the Database Research Group at the University of Tübingen, Germany.
There are 58 movies, most of them round a half-hour. They cowl subjects reminiscent of subqueries, set operations, GROUP BY extensions, knowledge sorts, arrays, window capabilities, user-defined capabilities, recursive CTEs, and plenty of, many extra.
5. SQL for Net Nerds
Hyperlink to useful resource: Philip Greenspun’s personal website
Description: This on-line e-book was written by Philip Greenspun, a US laptop scientist and educator.
It combines theoretical and sensible explanations via code and real-world examples. Most examples use the info mannequin for internet companies and are written in Oracle SQL dialect.
This useful resource will train you triggers, views, timber, database tunings, and plenty of extra.
Bonus: Nearly Free Sources
As a bonus, I needed so as to add two virtually free assets: StrataScratch (sure, the platform I based) and LeetCode, two platforms with precise SQL coding interview questions.
Nearly free, as in very low-cost? No, free in a manner that they require a paid subscription to entry all questions but in addition have a considerable variety of freemium questions.
We now have 75 free questions at StrataScratch, most of them of medium or arduous issue. You’ll positively discover a stable variety of them to check your superior SQL data. To make looking out simpler for you, there’s an in depth filter the place you possibly can filter by matter, issue, and firm, amongst different issues.
There’s additionally an interactive code editor for writing your answer in a number of SQL flavors (PostgreSQL, SQL Server, MySQL, and Oracle) and validating it. All of the questions have hints and official options with detailed explanations.
LeetCode has the identical variety of questions if I counted accurately. Nonetheless, they’re, typically, categorized as straightforward or medium, which might make in search of superior subjects just a little trickier. Nonetheless, I’m positive you’ll be capable to discover some good questions for training the subjects I discussed at first of this text. Like StrataScratch, LeetCode additionally has detailed options and an interactive code editor permitting code-writing in a number of SQL dialects.
Conclusion
There it’s – 5 assets that can train you superior SQL strategies and do it without cost. They’re additionally high quality assets, which makes for higher studying.
Three assets are basic on-line SQL programs that cowl totally different superior subjects. I threw within the combine one thing totally different, too: one YouTube course by a high German college and one on-line e-book by a acknowledged knowledgeable and educator.
A number of the subjects coated in these assets overlap, however some are distinctive to every useful resource. If you happen to don’t discover what you’re in search of in a single course, you possibly can at all times mix the assets and fill within the gaps.
As a bonus, there are two interview query platforms, StrataScratch and LeetCode, that supply some questions without cost.
I hope you’ll discover all these a priceless useful resource for studying superior SQL. Blissful studying!
Nate Rosidi is a knowledge scientist and in product technique. He is additionally an adjunct professor educating analytics, and is the founding father of StrataScratch, a platform serving to knowledge scientists put together for his or her interviews with actual interview questions from high corporations. Nate writes on the newest traits within the profession market, offers interview recommendation, shares knowledge science tasks, and covers every little thing SQL.
