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SQL Interview prep quiz 2 : Explain the difference between CTE and a subquery and give some advantages of using one over the other in OLAP vs OLTP systems

In this quiz, we are asked to give some differences between a common table expression and a subquery and what are some advantages of using one over the other in OLAP vs OLTP systems. This question is very loaded so we have to break it down apart and explain each component then piece it together. First of all we have to understand what is a CTE and a subquery. A common table expression (CTE) can…

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SQL interview prep quiz 1: Write sql code to print the letters of the English alphabet in upper case without explicitly writing the letters.

SQL interview prep quiz 1: Write sql code to print the letters of the English alphabet in upper case without explicitly writting the letters.

Hi guys, I am starting a new series on my blog around sql interview prep  questions and how to approach solving it.People have different approaches to solving problems so whatever approach l provide is just one of the ways of solving a problem and there could be other approaches that may be even be better and more optimized. Some interviewers will request you to provide a more optimized solution…

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Evaluating car class using the k nearest neighbor algorithm from the scikit-learn Machine learning library in Python

Evaluating car class using the k nearest neighbor algorithm from the scikit-learn Machine learning library in Python

In this post, I am going to give a quick tutorial how to use knn in sklearn to evaluate a car class. The dataset is from the UCI Machine learning repository https://archive.ics.uci.edu/ml/datasets/car+evaluation. You can download the dataset from this location from the data folder link to follow the tutorial. Also read more about the dataset and understand the description of the dataset. The…

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Differences between aggregation and composition in Python Class

Differences between aggregation and composition in Python Class

Have you heard the term aggregation or composition of classes in python? This can be a little tricky but let me share a simple scenario to explain the concept.

Let’s assume we have a class employee and another class salary. The salary class is has capability to calculate annual salary given the pay and the bonus.

So let’s create the salary class in python

class Salary: def __init__(self, pay,…

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How to use analytic functions First_value and Last_value introduced in SQL Server 2012

How to use analytic functions First_value and Last_value introduced in SQL Server 2012

I want to quickly go over some useful analytic functions introduced in sql server 2012 and how you can use it to accomplish some cool tasks in your data warehouse. Lets take a scenario where you have many employees who makes sales to various customers over the years. You are interested in generating report which gives you the employee with the highest sales and the one with the lowest sales each…

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How to use SQL Server extension ROLLUP to summarize data

How to use SQL Server extension ROLLUP to summarize data

As you you we have many functions for aggregating data in SQL such as AVG,MIN,MAX etc. Apart from this functions, there are sql server extension which can also be used to provide summarized data and give some powerful use of the data. In this post l will illustrate the operator called ROLLUP which is one of the four SQL Server extensions for summarizing data.

Take for example the data in the…

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Data profiling using SQL Server Integration Services - SSIS

Data profiling using SQL Server Integration Services – SSIS

Well, this is my first post in 2020 and it better be good and helpful to you out there. Happy new year!!!.

I want to discuss data profiling using SSIS in this post. If you are not familiar with data profiling, its a process of looking at a data set to make general sense of the data and its content. For example, l have a table called customers which has information on my customers containing the…

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OS questions

True or False and briefly explain why a) Cache is usually faster than main memory.

True.

Cache memory is directly connected to the central processing unit(CPU). Retrieval from cache takes far smaller amount of  CPU circles than retrieving from main memory. There is wait or delay for access to memory, which could take several CPU cycles because of the memory controller technology implemented in…

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English-Writing Dictionary

Argument

It is a set of meaningful sentences that can be true or false. This a good way of finding something to talk about in an essay. You can either agree or disagree and whatever side you are on, it’s good to state the reasons why you are on that side.

Arrangement

It is a canon of rhetoric that describes the other in which we want to say what we have decided to say. That is, what we want to…

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What is America?

The United States can be defined by its geographical position or its vast area of land, but in answering the above question, a unique phenomenon has touched my heart as one of the finest terms to describe America; that is immigration. Huge amounts of research have been done on immigration in America but I feel there’s much more to be discovered about the effects of this subject on America. As an…

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Biology Genetics Practice Problems

Biology Genetics Practice Problems

R= round    Y= yellow seeds    P = purple flowers    T = tall        G = green pods

r = wrinkled    y = green seeds    p = white flowers        t = short        g = yellow pods

   Show the cross and analyze the offspring from two homozygous parents, one of which is tall and one of which is short.

   Cross the offspring from #1 with a short parent.  Analyze the offspring.

   Cross two homozygous…

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Physics questions

Question 1.

A 6500-kg helicopter accelerates upward at 0.60 m/s² while lifting a 1200-kg car.

(a) What is the lift force exerted by the air on the rotors?

(b) What is the tension in the cable (ignore its mass) that connects the car to the helicopter?

Answer

a) The total mass that is accelerating at .60 m/s/s is the helicopter mass (6500 kg) and the car’s mass of 1200 kg or 7700 kg. The total…