Add further learning resources

index.qmd

@@ -82,6 +82,7 @@ You will not learn anything beyond *querying* data (table creation, modification
 nothing about windowing nor any of the specific more common table expressions.
 
 If you want to learn about those, there is a more reference-focused explanation available at [SQL Tutorial](https://www.sqltutorial.org/) which is a really nice next step when applying the mental maps passed along by the book this post is based on to new challenges and exploratory projects.
+I will try to point to some further SQL resources at the end of this post.
 Finally and, without further ado, let's get started.
 
 ## Chapter 1 - Individual operations {#sec-individual}
@@ -678,3 +679,24 @@ We also have not learned about the concepts of `window` functions or common tabl
 These are additional operations to get to know,
 but of course it is also important to get an overall broader view onto the concepts and mental mapping of SQL itself.
 The book closes with a call-to-challenge, with an additional dataset to knock your teeth on.
+
+If you are looking for more material to learn SQL or challenge yourself with:[^resources]
+
+- [SQL Tutorial](https://www.sqltutorial.org/):
+  I mentioned this one at the very beginning. 
+  It provides a next stepping stone and reference material for most of the blocks and expressions used in SQL.
+  It is less prosaic and project-bound than this book, but a good bookmark to keep at all times.
+- In a similar vein but completely geared towards SQLite, the [SQLite Tutorial](https://www.sqlitetutorial.net/).
+- Another fun resource, from basics to advanced with challenges along the way is provided on [SQLZoo](https://sqlzoo.net/wiki/SQL_Tutorial).
+  It may be a fun way to test some of the knowledge you already have now.
+- A short conceptual blog entry on [Common Table Expressions](https://www.dataknowsall.com/cte.html) which should give you the gist.
+  From here, perhaps you can start to think about how to incorporate them into the other projects.
+- Interactive practice sessions at [SQL Practice](https://www.sql-practice.com/).
+  You can follow along increasingly difficult sample exercises, or jump straight into whatever level or concept you feel the need to practice.
+- The Stanford-supplied long-form courses for [Beginner](https://online.stanford.edu/courses/soe-ydatabases0005-databases-relational-databases-and-sql) and [Advanced](https://online.stanford.edu/courses/soe-ydatabases0001-databases-advanced-topics-sql) SQL.
+  Obviously more of an investment than most of the previous ones.
+- And finally, more of a heavy hitter: A [book](https://bookwyrm.social/book/1517140/s/t-sql-querying-developer-reference) by Ben-Gan, teaching SQL by way of set theory to really grasp the underlying concepts.
+
+[^resources]: Mind you, I have *not* personally gone through all of the materials here,
+            they are the ones that I have either personally found really useful or someone
+            specifically recommended them to me.