While I began my SQL tutorial on w3schools, I decided to start tonight’s lessons using Professor Widom’s Stanford course as I found her explanations and examples easy to follow along with during the prior two courses. At first, I was a little worried that there would be a lot of repeats from what I learned on w3schools; however, I found that she started very differently. While w3schools started with simple examples of most aspects of database interaction (querying, modifying, deleting, inserting) before moving to more advanced versions, Professor Widom starts from the perspective of her relational algebra course and focused on analogies in SQL. I worked my way through the introduction, the basic select statement, table variables and set operators, subqueries in the where clause, and subqueries in the select and from clause. Most of this was new information, especially the use of set operators, multiple relations in FROM statements, and subqueries. I will admit that aspects of the subquery sections did confuse me and take a while to understand.
I still appreciate the w3schools tutorial because of how simple the layout is (especially with the clear-cut sections) and because of the simple tests at the end of each section, so I worked more on that too. Specifically, I went through the wildcards, in, between, aliases, and the different types of joins. This was also mostly new information and was a good supplement to the information gained through Professor Widom. I did find a little confusion in the joins, but I also noticed my next Widom course is on joins so I will not worry too much about those right now. Overall, I feel very confident in the basic mechanics of SQL especially when querying, but I feel like I still need practice working on more complicated queries and modifying the database. I also need to learn more about database creation, I guess I am still a little confused about where a database can reside since unlike other languages, I do not have a way (or at least know of a way) to test statements or clauses.