Fisseha Berhane, PhD

Data Scientist

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Managing big data with SQL


Working with databases in R

The dplyr package, which is one of my favorite R packages, works with in-memory data and with data stored in databases. In this post, I will share my experience on using dplyr to work with databases... more



Performing SQL selects on R data frames

For anyone who has SQL background and who wants to learn R, I guess the sqldf package is very useful because it enables us to use SQL commands in R. One who has basic SQL skills can manipulate data frames in R using their SQL skills... more



Using Amazon Relational Database Service with Python and R

Amazon Relational Database Service (RDS) is a distributed relational database service by Amazon Web Services (AWS). It simplifies the setup, operation, and scaling of a relational database for use in applications. In this blog post, we will see how to use R and Python with Amazon RDS. AWS RDS has a free tier for anybody to use for testing/development efforts... more.


Using PostgreSQL and shiny with a dynamic leaflet map: monitoring trash cans

When there is increased social activity, trash cans can get full quicker. On the contrary, during very cold weather, the trash cans can take one or a couple of more days to get full. Therefore, knowing when the trash cans are full lets us pick them up right away rather than waiting for a specific day of the week to come.

The code is available on GitHub



Using Subqueries and APPLY

This post is the sixth lab exercise I did on Querying with Transact-SQL edx course. I will use subqueries and the APPLY operator to retrieve data from the AdventureWorksLT database... more


Using Functions and Aggregating Data

This post is the fifth lab exercise I did on Querying with Transact-SQL edx course. I will write queries that use functions to retrieve, aggregate, and group data from the AdventureWorksLT database... more


Using Set Operators

This post is the fourth lab exercise I did on Querying with Transact-SQL edx course. I will use set operators to combine the results of multiple queries in the AdventureWorksLT database... more


Querying Multiple Tables with Joins

This post is the third lab exercise I did on Querying with Transact-SQL edx course. I will use joins to combine data from multiple tables in the AdventureWorksLT databas... more


Querying Tables with SELECT

This post is the second lab exercise I did on Querying with Transact-SQL edx course. I will use SELECT queries to retrieve, sort, and filter data from the AdventureWorksLT database... more


Introduction to Transact-SQL

This post is the first lab exercise I did on Querying with Transact-SQL edx course. I will use some basic SELECT queries to retrieve data from the AdventureWorksLT database... more


Joining Tables with Outer Joins

This post is the eigth lab exercise I did on Managing big data with MySQL coursera course... more


Joining Tables with Inner Joins

This post is the seventh lab exercise I did on Managing big data with MySQL coursera course... more


Summaries of Groups of Data

This post is the fifth lab exercise I did on Managing big data with MySQL coursera course. In this lesson, you are going to learn how to summarize multiple subsets of your data in the same query. The method for doing this is to include a "GROUP BY" clause in your SQL query... more


Summarizing Data

This post is the fourth lab exercise I did on Managing big data with MySQL coursera course. In this lesson we are going to learn how to use SQL to run calculations that summarize your data without having to output all the raw rows or entries... more


Formatting Selected Data

This post is the third lab exercise I did on Managing big data with MySQL coursera course. In this lesson, we are going to learn about three SQL clauses or functionalities that will help us format and edit the output of our queries. We will also learn how to export the results of our formatted queries to a text file so that we can analyze them in other software packages such as R or Python.... more


Using WHERE to select specific data

This post is the second lab exercise I did on Managing big data with MySQL coursera course. I will use WHERE to select specific data based on some criteria that include date, string and numeric constraints... more


Introduction to MySQL

This post is the first lab exercise I did on Managing big data with MySQL coursera course. I will use some basic SELECT queries to retrieve data from the MySQL server... more


Working with TERADATA

This post is a quiz I did with TERADATA on Managing big data with MySQL coursera course... more








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