Jan  Wisozk

Jan Wisozk


Data Science SQL Scenario Based Interview Question [Facebook] - Date Manipulation

This Data Science SQL interview question is from Facebook, and tests your ability to filter out data based on date conditionals. I’ll walk you through solving the question like we’re in an interview and give you some tips on how to approach the solution as well as how to efficiently and effectively communicate with your interviewer.

Go to the question through the link below and follow along with me.

Link to the question: https://bit.ly/3eC68eT


  • Intro: (0:00​​​)
  • Interview Question: (0:33​​)
  • Framework to solve the problem: (1:08​​​)
  • Understand your data: (2:25​​​)
  • Formulate your approach: (4:16​​​)
  • Code Execution: (6:15​​​)
  • Additional Technical Concepts: (11:56​​​)
  • Conclusion: (14:40​​​)

#sql #data-science #interview-questions

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Data Science SQL Scenario Based Interview Question [Facebook] - Date Manipulation
Cayla  Erdman

Cayla Erdman


Introduction to Structured Query Language SQL pdf

SQL stands for Structured Query Language. SQL is a scripting language expected to store, control, and inquiry information put away in social databases. The main manifestation of SQL showed up in 1974, when a gathering in IBM built up the principal model of a social database. The primary business social database was discharged by Relational Software later turning out to be Oracle.

Models for SQL exist. In any case, the SQL that can be utilized on every last one of the major RDBMS today is in various flavors. This is because of two reasons:

1. The SQL order standard is genuinely intricate, and it isn’t handy to actualize the whole standard.

2. Every database seller needs an approach to separate its item from others.

Right now, contrasts are noted where fitting.

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Sasha  Lee

Sasha Lee


Facebook and Microsoft Data Science SQL Interview Questions

Data science roles at Facebook and Microsoft are highly competitive and difficult to land. Writing SQL on the job will cover 100% of the problems you’re going to handle in practice. In this article, we’ll walk through solving the data science SQL interview question from Microsoft and Facebook. We’ll also give you some tips on how to approach the solution in such data science interviews.

Data Science SQL Interview Question

New And Existing Users

Calculate the share of new and existing users. Output the month, share of new users, and share of existing users as a ratio.

New users are defined as users who started using services in the current month. Existing users are users who started using services in the current month and used services in any previous month.

Assume that the dates are all from the year 2020.

5-Step Framework to Solve this Interview Question

This framework can be used for any data science SQL interview question. Here’s a list of steps you should take when solving a question, whether on an interview or on the job.

  1. Explore Data
  2. **a) **Only when we’re on the job as most of the time you won’t have executable IDEList assumptions
  3. List Assumptions
  4. **a) **Listing assumptions helps you narrow down the solution space. It’ll help you identify edge cases and limit your solution to the bounds of your assumption.
  5. Outline Approach
  6. **a) **Outline the approach by writing it out in steps. Each step is one logical statement or business rule.
  7. b) Confirm these steps with the interviewer. Often, if the interviewer spots something wrong, they’ll bring it up which is nice because you can fix the problem before even writing a line of code.
  8. c) If you want, you can mention the functions you’d implement to solve the problem.
  9. Code in Increments
  10. **a) **Build the solution in logical parts and communicate each part so the interviewer knows what you’re doing.
  11. b) Your code needs to be logical and well structured. The most important point is not to put more than 1 logical statement or business rule for each “block” of code. A block of code can be defined as a CTE or a subquery because it’s self-contained and separate from the rest of the code.
  12. Optimize Code
  13. **a) **This is usually just a conversation with the interviewer but on the job, you will usually refactor the code to run more efficiently if the code would be used repeatedly.

#data-science-interview #sql-interview-questions #sql-interview #data-science #facebook

Uriah  Dietrich

Uriah Dietrich


How To Build A Data Science Career In 2021

For this week’s data science career interview, we got in touch with Dr Suman Sanyal, Associate Professor of Computer Science and Engineering at NIIT University. In this interview, Dr Sanyal shares his insights on how universities can contribute to this highly promising sector and what aspirants can do to build a successful data science career.

With industry-linkage, technology and research-driven seamless education, NIIT University has been recognised for addressing the growing demand for data science experts worldwide with its industry-ready courses. The university has recently introduced B.Tech in Data Science course, which aims to deploy data sets models to solve real-world problems. The programme provides industry-academic synergy for the students to establish careers in data science, artificial intelligence and machine learning.

“Students with skills that are aligned to new-age technology will be of huge value. The industry today wants young, ambitious students who have the know-how on how to get things done,” Sanyal said.

#careers # #data science aspirant #data science career #data science career intervie #data science education #data science education marke #data science jobs #niit university data science

'Commoditization Is The Biggest Problem In Data Science Education'

The buzz around data science has sent many youngsters and professionals on an upskill/reskilling spree. Prof. Raghunathan Rengasamy, the acting head of Robert Bosch Centre for Data Science and AI, IIT Madras, believes data science knowledge will soon become a necessity.

IIT Madras has been one of India’s prestigious universities offering numerous courses in data science, machine learning, and artificial intelligence in partnership with many edtech startups. For this week’s data science career interview, Analytics India Magazine spoke to Prof. Rengasamy to understand his views on the data science education market.

With more than 15 years of experience, Prof. Rengasamy is currently heading RBCDSAI-IIT Madras and teaching at the department of chemical engineering. He has co-authored a series of review articles on condition monitoring and fault detection and diagnosis. He has also been the recipient of the Young Engineer Award for the year 2000 by the Indian National Academy of Engineering (INAE) for outstanding engineers under the age of 32.

Of late, Rengaswamy has been working on engineering applications of artificial intelligence and computational microfluidics. His research work has also led to the formation of a startup, SysEng LLC, in the US, funded through an NSF STTR grant.

#people #data science aspirants #data science course director interview #data science courses #data science education #data science education market #data science interview

Top 130 Android Interview Questions - Crack Technical Interview Now!

Android Interview Questions and Answers from Beginner to Advanced level

DataFlair is committed to provide you all the resources to make you an android professional. We started with android tutorials along with practicals, then we published Real-time android projects along with source code. Now, we come up with frequently asked android interview questions, which will help you in showing expertise in your next interview.

android interview questions

Android Interview Questions – Get ready for your next interview

Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.

Android Interview Questions for Freshers

1. What is Android?

Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.

2. Who is the inventor of Android Technology?

The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.

3. What is the latest version of Android?

The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]

4. How many Android versions can you recall right now?

Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:

  • Android 1.0 – Its release is 23 September 2008.
  • Android 1.1 – Its release date is 9 February 2009.
  • Android 1.5 – Its name is Cupcake, Released on 27 April 2009.
  • Android 1.6 – Its name is Donut, Released on 15 September 2009.
  • Android 2.0 – Its name is Eclair, Released on 26 October 2009
  • Android 2.2 – Its name is Froyo, Released on 20 May 2010.
  • Android 2.3 – Its name is Gingerbread, Released on 06 December 2010.
  • Android 3.0 – Its name is Honeycomb, Released on 22 February 2011.
  • Android 4.0 – Its name is Ice Cream Sandwich, Released on 18 October 2011.
  • Android 4.1 – Its name is Jelly Bean, Released on 9 July 2012.
  • Android 4.4 – Its name is KitKat, Released on 31 October 2013.
  • Android 5.0 – Its name is Lollipop, Released on 12 November 2014.
  • Android 6.0 – Its name is Marshmallow, Released on 5 October 2015.
  • Android 7.0 – Its name is Nougat, Released on 22 August 2016.
  • Android 8.0 – Its name is Oreo, Released on 21 August 2017.
  • Android 9.0 – Its name is Pie, Released on 6 August 2018.
  • Android 10.0 – Its name is Android Q, Released on 3 September 2019.
  • Android 11.0 – As of now, it is Android 11.

5. Explain the Android Architecture with its components.

This is a popular android developer interview question

Android Architecture consists of 5 components that are-

a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.

b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.

c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.

d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.

e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.

6. What are the services that the Application framework provides?

The Android application framework has the following key services-

a. Activity Manager: It uses testing and debugging methods.

b. Content provider: It provides the data from application to other layers.

c. Resource Manager: This provides users access to resources.

d. Notification Manager: This gives notification to the users regarding actions taking place in the background.

e. View System: It is the base class for widgets, and it is also responsible for event handling.

7. What are the important features of Linux Kernel?

The important features of the Linux Kernel are as follows:

a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.

b. Memory Management: It is useful for the maximum utilization of the available memory of the device.

c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.

d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.

e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.

8. What are the building blocks of an Android Application?

This is a popular android interview question for freshers.

The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:

a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.

b. Services- Services are the longest-running component that runs in the background.

c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.

d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.

9. What are the important components of Android Application?

The Components of Android application are listed below:

  1. Widgets
  2. Intents
  4. Notification
  5. Fragments
  6. Layout XML files
  7. Resources

10. What are the widgets?

Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.

11. Can you name some types of widgets?

Mentioned below are the types of widgets-

a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.

b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.

c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.

d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.

12. What are Intents?

Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.

13. Explain the types of intents briefly?

Intent is of three types that are-

a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.

b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.

c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.

14. What is a View?

A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.

15. What do you understand by View Group?

It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.

16. What do you understand about Shared Preferences?

It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.

17. What is a Notification?

A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.

18. Give names of Notification types.

There are three types of notifications namely-

a. Toast Notification- This notification is the one that fades away sometime after it pops up.

b. Status Notification- This notification stays till the user takes some action on it.

c. Dialog Notification- This notification is the result of an Active Activity.

19. What are fragments?

A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.

20. What are the types of fragments?

There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.

  1. Single Transactions can only show a single view for the user.
  2. List Fragments have a special list view feature that provides a list from which the user can select one.
  3. Fragment Transactions are helpful for the transition between one fragment to the other.

Frequently asked Android Interview Questions and Answers

21. What are Layout XML files?

Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.

22. What are Resources in Android Application?

The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.

23. Can you develop Android Apps with languages other than Java? If so, name some.

Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.

24. What are the states of the Activity Lifecycle?

Activity lifecycle has the following four stages-

a. Running State: As soon as the activity starts, it is the first state.

b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.

c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.

d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.

25. What are some methods of Activity?

The methods of Activity are as follows:

  • onCreate()
  • onStart()
  • onPause()
  • onRestart()
  • onResume()
  • onStop()
  • onDestroy()

26. How can you launch an activity in Android?

We launch an activity using Intents. For this we need to use intent as follows:

  1. ntent intent_name= new Intent(this, Activity_name.class);
  2. startActivity(intent_name);

27. What is the service lifecycle?

There are two states of a service that are-

a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.

b. Bounded State: A service is in the bounded state when it calls the method bindService().

28. What are some methods of Services?

The methods of service are as follows-

  • onStartCommand()
  • onBind()
  • onCreate()
  • onUnbind()
  • onDestroy()
  • onRebind()

29. What are the types of Broadcast?

Broadcasts are of two types that are-

a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.

b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.

30. What are useful impotent folders in Android?

The impotent folders in an Android application are-

  1. build.xml- It is responsible for the build of Android applications.
  2. bin/ – The bin folder works as a staging area to wrap the files packages into the APK.
  3. src/ – The src is a folder where all the source files of the project are present.
  4. res/ – The res is the resource folder that stores values of the resources that are used in the application. These resources can be colors, styles, strings, dimensions, etc.
  5. assets/ – It provides a facility to include files like text, XML, fonts, music, and video in the Android application.

31. What are the important files for Android Application when working on Android Studio?

This is an important android studio interview question

There are following three files that we need to work on for an application to work-

a. The AndroidManifest.xml file: It has all the information about the application.

b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.

c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.

32. Which database do you use for Android Application development?

The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.

33. Tell us some features of Android OS.

The best features of Android include-

  1. Multi-tasking
  2. Support for a great range of languages
  3. Support for split-screen
  4. High connectivity with 5G support
  5. Motion Control

34. Why did you learn Android development?

Learning Android Studio is a good idea because of the following-

  1. It has a low application development cost.
  2. It is an open-source platform.
  3. It has multi-platform support as well as Multi-carrier support.
  4. It is open for customizations.
  5. Android is a largely used operating system throughout the world.

35. What are the different ways of storage supported in Android?

The various storage ways supported in Android are as follows:

  1. Shared Preference
  2. Internal Storage
  3. External Storage
  4. SQLite Databases
  5. Network Connection

36. What are layouts?

Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.

37. How many layout types are there?

The type of layouts used in Android Apps are as follows:

  1. Linear Layout
  2. Relative Layout
  3. Constraint Layout
  4. Table Layout
  5. Frame Layout
  6. Absolute Layout
  7. Scrollview layout

38. What is an APK?

An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.

39. What is an Android Manifest file?

The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.

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