My Exam 3 review notes for CIS4301 Spring 2014. This repository is here in an effort to help crowdsource exam review notes. Please submit pull requests to improve/add content.

##Topics To-Do

Thanks to Eric Gross for the topic list:

• JDBC
  • Cursor in database.
    • It is an iterator, also the same as the ResultSet(Java).
  • PreparedStatements are faster because it's already partially parsed, and all you have to do is just insert a value where the '?' is placed within the prepared statement.
  • Reflection Statement - Where the driver is.
• Query with EXPLAIN & ANALYZE
  • EXPLAIN gives the tree of the query plan.
    • Start-up Cost | Estimated Cost | rows & width in bytes.
  • ANALYZE gives back the analysis of the query plan.
• Know steps of K-Means
  1. Choose K - # of clusters.
  2. Randomly place centroids.
  3. Assign Points to centroids.
  4. Average of all the points for each centroid.
  5. Update the location of centroids.
  6. Repeat 3 - 6 until no more updates on centroids.
• Know use-cases of K-Means.
  • Group together data with similar information and how they're relevant.
  • Can group what type of data is being grouped togehter
    • i.e., types of dogs, age and salary of people.
  • Things within a cluster are similar.
  • Things between clusters are dis-similar.
  • When do you have the best K?
    • Check the average distance between the points and the centroids.
    • If the distances withinthe sae cluster are close, then it's a good K.
    • Find the K that is right at the downslope of the curve.

##Topics Done

Please update when you submit a pull request with new information.

• HTML

  • FORMS
  • SUBMIT
  • USING A METHOD (GET & POST)
    • Know the difference between the two.
    • Use POST for putting stuff into a database.
    • Use GET to just retrieve data from database.
    • Users can easily change GET requests in the URL.
    • GET requests store the information in the URL.
  • #/some_URL - Takes you to the div(id = 'some_URL')

• Map Reduce

  • Know the stages.
    • Map
    • Reduce
    • Shuffle
  • Know what a functional map-reduce is.
    • Takes a function and does a map reduce of it.