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The web is brimming with sources for studying SQL. Most of them, in fact, require paying for data. These sources additionally primarily train you primary or, at finest, intermediate SQL.
The query is, learn how to study SQL and do it at no cost. Are there any sources in any respect that can train you superior SQL with out paying?
Sure, there are. In actual fact, there are at the 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 instructing expertise) on which SQL ideas might be thought-about superior.
Nonetheless, I feel it’s secure to say that these matters are superior SQL:
- JOINs
- CTEs
- Recursive CTEs
- Subqueries and Correlated Subqueries
- Window Features
- Pivoting and Unpivoting Knowledge
- Hierarchical Queries
- Views
- Saved & Person-Outlined Procedures and Features
- Triggers
- Short-term Tables
- Indexes
- Knowledge Normalization
- Efficiency Optimization
The record is incomplete, nonetheless. Another matters that additionally belong to superior SQL might be added. How will you say in the event that they’re superior? I’ve a extremely unscientific however environment friendly methodology: if you happen to don’t know what a specific subject means, it’s almost definitely superior SQL.
Free Sources for Superior SQL
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The sources I record right here cowl some or many of the superior SQL ideas I discussed earlier. In case you mix these sources, your superior SQL data can grow to be 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 software. No want to fret that you just’ll must study 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 observe fixing issues by writing SQL queries and examine the solutions.
Talking of ideas, you’ll find out about subqueries, window features, tuning SQL queries, and pivoting knowledge. As well as, there are classes about knowledge sorts, date codecs, and string features.
In case you really feel you’re combating among the much less superior matters 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 Matters 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 matters, you’ll be taught indexing to enhance question efficiency, transactions, database constraints and triggers, and views.
It’s going to 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 principle, and semistructured knowledge if you happen to’re all in favour of these matters.
3. Kaggle Superior SQL
Hyperlink to useful resource: Kaggle Superior SQL
Description: Kaggle’s cute little course will take solely 4 hours to finish. It covers JOINs and UNIONs, analytic (or window) features, nested and repeated knowledge, and tips about writing environment friendly queries.
Every lesson supplies detailed theoretical explanations complemented by sensible examples. On the finish of every lesson, you will see that a hyperlink to a bit that checks 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 Analysis Group on the College of Tübingen, Germany.
There are 58 movies, most of them round a half-hour. They cowl matters resembling subqueries, set operations, GROUP BY extensions, knowledge sorts, arrays, window features, user-defined features, recursive CTEs, and lots of, many extra.
5. SQL for Net Nerds
Hyperlink to useful resource: Philip Greenspun’s private web site
Description: This on-line e-book was written by Philip Greenspun, a US laptop scientist and educator.
It combines theoretical and sensible explanations by means of code and real-world examples. Most examples use the information mannequin for net providers and are written in Oracle SQL dialect.
This useful resource will train you triggers, views, timber, database tunings, and lots of extra.
Bonus: Nearly Free Sources
As a bonus, I wished so as to add two virtually free sources: 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 method that they require a paid subscription to entry all questions but in addition have a considerable variety of freemium questions.
Now we have 75 free questions at StrataScratch, most of them of medium or onerous issue. You’ll positively discover a strong 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 subject, issue, and firm, amongst different issues.
There’s additionally an interactive code editor for writing your resolution 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 appropriately. Nonetheless, they’re, most often, categorized as straightforward or medium, which may make in search of superior matters somewhat trickier. However, I’m certain you’ll be capable of discover some good questions for practising the matters I discussed initially 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 sources that can train you superior SQL strategies and do it at no cost. They’re additionally high quality sources, which makes for higher studying.
Three sources are basic on-line SQL programs that cowl totally different superior matters. 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 skilled and educator.
Among the matters coated in these sources overlap, however some are distinctive to every useful resource. In case you don’t discover what you’re in search of in a single course, you possibly can at all times mix the sources and fill within the gaps.
As a bonus, there are two interview query platforms, StrataScratch and LeetCode, that provide some questions at no cost.
I hope you’ll discover all these a useful useful resource for studying superior SQL. Completely satisfied studying!
Nate Rosidi is an information scientist and in product technique. He is additionally an adjunct professor instructing 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 firms. Nate writes on the newest developments within the profession market, provides interview recommendation, shares knowledge science tasks, and covers every thing SQL.
