Mike Divine's Learning Journal

Here are five of the things I have learned in this course so far.  One is that databases are very useful for organizing data effeciently as well as finding and formatting data quickly.  Two is that you can join tables together to pull data together and see much more data concurrently.  Three is that you can create temporary tables called Views that you can use to pull pertinent data more easily.  Four is that you can select data from other sub select statements which allows you to do things otherwise unavailable.  Five is that you can alter tables and change them in the future if needed. Here are three of the thing I would like to learn about.  First is I would like to learn about Big Data databases as I have heard a lot of references to them and I am not really sure about how they differ and what they are useful for.  Second is I would like to learn more in depth about how to do complex data pulls as I still struggle sometimes to figure out how to get...

    3rd Normal Form is making sure all the data is stored in a way where updates to a database can be done without having to update data in multiple locations.  This will help so mistakes are not introduced where data is thought to have been updated but then outdated or incorrect information can still be pulled without realizing it.  Creating Primary Keys and Foreign keys which rely on other table's Primary Keys ensures data integrity is kept.  Also, you should not have to store the same data in multiple table except for those keys.     A SQL View is a temporary table that pulls data from the actual live database tables.  It is used only for an existing query and is recreated every time you pull data from the View.  It is very similiar to a table except that the table is actually stored on the server and the View is pulled from the database and then stored into the View on the client side.

I was thinking that joining tables on something other than primary keys and foreign keys would not be something that should exist, but I guess you never know what you would eventually want to use data for.  An example I thought of was having to join tables with populations if the tables weren't related in another way. Join a table countries with population and then a table cities with population.   SELECT ci.Name AS city, c.Name AS country, c.population FROM city ci, country c; SQL language is not that easy to learn.  It is fairly simple to learn the basics but figuring out how to do specifics with large datasets can be very complicated and hard to grasp.  The questions I find most challenging are trying to pull specific data and trying to figure out how to get only that data and format it the way you want.

     This week we learned about how a (DBMS) Database Management System works and how to create tables, insert data, delete data, and pull data using SELECT, DELETE, CREATE, and UPDATE commands.     Databases are different from spreadsheets because the data are stored in tables that are relational and use key values to link to other tables.  Some other differences are that spreadsheets often times have formatted data and it is harder to access and manipulate.  Databases store data without formatting.  Also there are many different ways to access the data and only pull out the data you need within databases.      There are many reasons to store data in a database rather than just in a file system.  You can pull data more easily by querying the database and find data much more quickly.  You can join tables to pull data together and organize it the way you would like.  Databases can also handle a lot of data and access i...