Liam's Computer Science Learning Journal

  This week is halfway through the course.  Briefly summarize 5 things what you have learned in the course so far.   List at least 3 questions you still have about databases. Summary of standout learning moments: I have been grateful to learn how databases are structured to store, organize, retrieve, and filter data efficiently. Realizing the extent of database necessity and prevalence in a hands-on and versatile way has revealed how databases are the backbone of software, and--by transitive property--information in a world that persists to move away from any form of physical database. Learning about the relational model and schemas has been eye opening in visualizing how data is manipulated and impacted by structural design. Defining schema and using keys to ensure data integrity in both Java and MySQL have provided different perspectives on the same landscape, providing a well-rounded approach to building further knowledge. Writing a range of simple and complex que...

What is an SQL view.  How is it similar to a table? In what ways is it different (think about primary keys,  insert, update, delete operations) ? A view in SQL acts as a fixed and somewhat imaginary table that limits operations done on data and is mostly intended for database users who are not changing data but instead simply accessing it. A view is created with a select statement that will define what can be viewed from the view. Because a view is driven by a pre-defined separate query, it can encapsulate a query that will be reused elsewhere in more complex searches. A few immediate differences between the two are the lack of direct primary and foreign keys when compared to a table. The table is holding the constraints and indexes while the view simply reveals what the underlying table has already established. As the name suggests, a view simply is a view and does not store data the way a table does. Because of these former two facts, insert/update/delete statements are gene...

SQL has the flexibility to join tables on any column(s) using any predicate (=, >, < ).    Most of the time the join will use equality between a primary and foreign key.   Think of example where joining on something other than keys would be needed.  Write the query both as an English sentence and in SQL.  If you can't think of your own example, search the textbook or internet for an example. Let's say we want to use a SQL query to count the number of  attack moves that a Pokémon can learn based on its elemental type (like Fire, Water, etc.). We can join the Monster table (representing Pokémon) with the Moveset table (representing available moves/attacks that monster can learn) based on the matching elemental type , even though the move isn't linked by ID to the Pokémon or the move itself. This allows for Pokémon to learn moves outside of their elemental type (which might be tied to the ID) as well as the moves available to them via matching ty...

From the orientation, your reading from week 1, and your own experience answer the following questions: Relational database tables and spreadsheets look similar with both having rows and columns.  What are some important differences between the two? At first glance, a relational database and a spreadsheet in an application such as Excel look fairly commensurate to each other in purpose and functionality--they both are comprised of rows and columns that hold data organized by column names and row numbers. The truth is that their visual similarity is where the commensuration ends and the vast differences begin. Relational databases adhere to strict and organized rules that ensure they can manage large volumes of structured data as well as complex queries to return results from that data whereas spreadsheets can be filled out arbitrarily. Foreign keys and primary keys can tie individual values or sets of values to other tables of data which in turn impact how data can be returned or c...