Chapter 6 of Allen Tucker’s Client-Centered Software Development discusses the importance and usage of databases to software development. He begins by giving a brief explanation of the different kinds of databases and then introduces the reader to SQL and its different implementations. The rest of the chapter is essentially spent explaining the functionality and syntax of SQL. This, of course, was good for me because I admittedly haven’t worked with SQL since last summer when I was making my web scraping application for professional esports players’ game stats. One thing that was brand new which I came across was how concurrency controls are managed by different DBMS’s. I was unaware of row and table level locking, although something tells me we may have touched on this in databases and I just forgot. I definitely hadn’t heard of MVCC though, where the table, in order to take multiple queries at once, simply gives access to a “snapshot” of the table from the past. That way, any access of the database granted would not be influenced by other modifications within a specified time interval.
For our contributions to Open Library, we haven’t worked with the backend or databases, but the JavaScript we’ve worked with does use data retrieved from the databases. A lot of my time to my most recent commit was spent on figuring out (and receiving help with) how to get data from the database into the JavaScript I was moving away from HTML pages. Basically, the inline JavaScript had before been passed from the server to the user with the data from the server already inserted into the logic of the program. After the changes I made, the HTML is passed to the user with the needed data from the server and then the JavaScript, passed to a user in a separate file, parses the DOM to look for special attributes using jQuery to find the server data needed for the frontend.
Noah Drake's Blog 