Q16 What Is A Subquery In Sqlwhat Are The Different Types Of A Subquery
Ans. A subquery is a query within another query. When there is a query within a query, the outer query is called the main query, while the inner query is called a subquery. There are two types of a subquery:
- Correlated subquery: It obtains values from its outer query before it executes. When the subquery returns, it passes its results to the outer query.
- Non-Correlated subquery: It executes independently of the outer query. The subquery executes first and then passes its results to the outer query. Both inner and outer queries can run separately.
So How To Prepare For Amazon Data Engineer Interview
Plan, Practice, Strategize and give your best. We know that interviews are tough, but keep pushing through it, and your dream job will be a reality soon. There are tons of resources online that can help you achieve this goal. Benefit from them and make yourself technically capable.
The industry is always in search to come across talent that fits them in all aspects. Adapt according to the organization and make sure your skills are rock solid. We hope this article covered all your questions about how to prepare for Amazon Data Engineer Interview. Good luck.
Amazon Sql Interview Questions
Amazon, one of the most sought-after and renowned FAANG companies, has a spectrum of opportunities to offer. And like any other tech giant, Amazon also receives a huge amount of applications from around the globe. The journey to get past the competition and land a job at Amazon is challenging. So, if you are a software engineer, a software developer, a data engineer, an engineering manager, or a tech lead gunning for a job at Amazon, then this article is for you!
If you are preparing for a tech interview, check out our interview questions page and salary negotiation ebook to get interview-ready! Also, read and for specific insights and guidance on Amazon Tech interviews.
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We are here to make the exhaustive process of preparing for a tech interview or a coding interview easier for you. Before we dive into the process, remember this: preparation is the key to success.
In this article, weâll cover:
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Make Sure You Understand The Role You Have Applied To And Are Prepared For The Basic Questions
Data Engineering is a vast feel. Leave no stone unturned to understand all the details of the job description.
Interpret the skills needed for the role. Regardless of the type of interview, always prepare yourself for Technical Questions, Programming tests, Design Questions, and Behavioural questions.
The domains involved are:
Common Sql Interview Questions For Amazon
This section will serve as your âgo-to SQL interview prep guide,â as we have covered the most commonly asked SQL interview questions at Amazon. In addition to getting well-versed in Amazon SQL interview questions, it is also suggested to brush up on your problem-solving skills, as it comes in handy during FAANG interviews.
Sample answer: SQL stands for Structured Query Language, and as the name suggests, it is a language used by database administrators to communicate with the database. The administrator inputs a query in the form of a string of commands to search for values in a database.
Sample answer: Amazon database is one of the Amazon Web Services, which is a fully managed petabyte-scale data warehouse service. There are various Amazon Database Services available, such as DynamoDB, RDS, ElastiCache, and RedShift.
Sample answer: Auto Scaling is a specialized feature of DynamoDB that allows it to automatically scale up and down the global secondary index or its own read and write.
Sample answer: Inner join is the default join, which is used when no join is specified.
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Q30 List The Ways To Get The Count Of Records In A Table
To count the number of records in a table in SQL, you can use the below commands:
SELECT * FROM table1SELECT COUNT FROM table1SELECT rows FROM sysindexes WHERE id = OBJECT_ID AND indid < 2
Apart from this SQL Interview Questions Blog, if you want to get trained from professionals on this technology, you can opt for structured training from edureka!
How To Delete A Row In Sql
We will be using the DELETE query to delete existing rows from the table:
DELETE FROM table_name
We will start off by giving the keywords DELETE FROM, then we will give the name of the table, after that we will give the WHERE clause and give the condition on the basis of which we would want to delete a row.
For example, from the employee table, if we would like to delete all the rows, where the age of the employee is equal to 25, then this will the command:
DELETE FROM employee
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How Did I Crack Interviews Of Google Facebook Amazon And How You Could Do It Too
In this article, my aim is not to tell what questions I was asked as that might not help you a lot. Here Ill try to focus on how I prepared and what worked for me. You might want to try the same if you are targeting any FAANG or a similar company.
There are three main skill sets that all of these companies test the candidates on:
For each of these skill sets, Ill try to cover the below three aspects that would be important for your interviews:
Basic Sql Whiteboard Questions For Job Interviews
First, letâs focus on the more theoretical side of SQL. To assess your understanding here, the recruiter will likely ask you to verbally explain some simpler questions. These are usually mainly about the elementary parts of SQL. For example, you might be asked to answer some of the following SQL whiteboard questions:
- What does UNION do? What is the difference between UNION and UNION ALL?
- What do the INTERSECT and MINUS clauses do?
- What is the role of the DISTINCT keyword?
- Explain the use of aliases in queries.
Can you answer every question from my SQL practice for interviews? Even basic questions need good preparation and a lot of practice. Nobody is perfect, and sometimes you need to refresh your knowledge. our online courses can help you brush up on any semi-forgotten skills.
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Q5 What Are Joins In Sql
A JOIN clause is used to combine rows from two or more tables, based on a related column between them. It is used to merge two tables or retrieve data from there. There are 4 types of joins, as you can refer to below:
- Inner join:Inner Join in SQL is the most common type of join. It is used to return all the rows from multiple tables where the join condition is satisfied.
Left Join: Left Join in SQL is used to return all the rows from the left table but only the matching rows from the right table where the join condition is fulfilled.
Right Join: Right Join in SQL is used to return all the rows from the right table but only the matching rows from the left table where the join condition is fulfilled.
Full Join: Full join returns all the records when there is a match in any of the tables. Therefore, it returns all the rows from the left-hand side table and all the rows from the right-hand side table.
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Sql Exercise 2 Write A Statement
Write an SQL statement that lists student names, subject names, subject lecturers, and the max amount of points for all subjects except Computer Science and any subjects with a max score between 100 and 200.
Table: subjectsubject_id subject_name max_score lecturer---------- ---------- ---------- ----------- 11 Math 130 Christena Solem 12 Computer Science 150 Jaime Pille 13 Biology 300 Carrol Denmark 14 Geography 220 Yuette Galang 15 Physics 110 Colton Rather 16 Chemistry 400 Nan Mongeau
Table: studentstudent_id student_name city subject_id----------- ------------ ---------- -----------2001 Thurman Thorn New York 112002 Sharda Clemens San Francisco 122003 Buck Elkins New York 132004 Fabian Johns Boston 152005 Brad Cameron Stanford 112006 Sofia Roles Boston 162007 Rory Pietila New Haven 12
Walking Through My Thinking
Apple, Amazon, and Facebook included this question in their Data Science Interviews. It is a straightforward question that asks for the rank with no holes or jumps between ranks.
In SQL, there are two ways of handling ranks: rank and dense_rank. The difference is the dense_rank command does not skip ranks and the rank command skips ranks if there are ties.
The question statement explicitly tells us that there should be no holes between ranks after a tie, which makes dense_rank an obvious choice. If another question does not provide such a friendly hint, remember to ask your interviewers to clarify what to do for ties. They are expecting you to ask questions if they intentionally exclude such a critical piece of information.
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Q5 How Do You Allocate And Deallocate Memory In C++
The new operator is used for memory allocation and deletes operator is used for memory deallocation in C++.
< /pre> int value=new int //allocates memory for storing 1 integerdelete value // deallocates memory taken by valueint *arr=new int //allocates memory for storing 10int delete arr // deallocates memory occupied by arr< pre>
Be prepared with many such questions for your technical round. You can refer websites like Hackerrank and other coding website, they are a good place for more such questions. Adding GitHub Link in your linkedin profile or resume will also help, try including your projects there. Now lets move on, in this Amazon Interview Questions blog Amazon has strong work ethics, which is reflected in their Amazon Leadership Principles. As an employee, no matter at which stage of your career you are joining, they expect you to show some leadership qualities when you work. Following are the amazon leadership principles which you will be checked for before you are hired for the role.
What Are The Types Of Views In Sql
In SQL, the views are classified into four types. They are:
A view that is based on a single table and does not have a GROUP BY clause or other features.
A complex view is one that is built from several tables and includes a GROUP BY clause as well as functions.
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Screening Interview Over The Phone
Everything starts with a short, screening interview. An HR employee will call you and ask you a few basic questions. To such belong:
- Why are you interested to work at Amazon?
- How do you imagine a typical day in this job?
- Tell me something about yourself.
- What motivates you in work?
- Which Amazon leadership principle resonates the most with you, and why?
- What do you like the most about Amazon? What do you do not like?
Their goal in a screening interview is to assess your communication skills, your motivation, and to understand your personality and attitude to work, whether it aligns with the 14 leadership principles they promote at Amazon.
A good HR worker can do that after a ten to twenty minute phone call with youthey can get a basic grasp of your personality and abilities. And how should you answer the questions? Lets have a look at one of them.
Q17 What Are Entities And Relationships
Entities: A person, place, or thing in the real world about which data can be stored in a database. Tables store data that represents one type of entity. For example A bank database has a customer table to store customer information. The customer table stores this information as a set of attributes for each customer.
Relationships: Relation or links between entities that have something to do with each other. For example The customer name is related to the customer account number and contact information, which might be in the same table. There can also be relationships between separate tables .
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Q2 What Are The Different Subsets Of Sql
- Data Definition Language It allows you to perform various operations on the database such as CREATE, ALTER, and DELETE objects.
- Data Manipulation Language It allows you to access and manipulate data. It helps you to insert, update, delete and retrieve data from the database.
- Data Control Language It allows you to control access to the database. Example Grant, Revoke access permissions.
Sql Exercise 9 Write A Complex Query
Write a query that lists coursesâ subject names and the number of students taking the course only if the course has three or more students enrolled.
Table: subjectsubject_id subject_name max_score lecturer---------- ---------- ---------- ----------- 11 Math 130 Christena Solem 12 Computer Science 50 Jaime Pille 13 Biology 300 Carrol Denmark 14 Geography 220 Yuette Galang 15 Physics 110 Colton Rather 16 Chemistry 400 Nan Mongeau
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Q5 What Is The Primary Key
Ans. A primary key constraint uniquely identifies each row/record in a database table. Primary keys must contain unique values. Null value and duplicate values are not allowed to be entered in the primary key column. A table can have only one primary key. It can consist of single or multiple fields.
All Set To Crack Your Next Amazon Sql Interview
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We aim to help engineers get acquainted with their chosen fieldâs intricacies and provide them with all the required guidance to ace their interviews with tech giants. Our programs are tailored to specific domains, including Data Engineering, so that you can sail through every round of the interview.
Clearing an interview requires much more than sound technical knowledge â so, we train you in a manner that helps you develop a winner’s stride. IK is the golden ticket for all the budding engineers who wish to land the job they deserve.
Describe How To Delete Duplicate Rows Using A Single Statement But Without Any Table Creation
Lets create an Employee table where column names are ID, NAME, DEPARTMENT, and EMAIL. Below are the SQL scripts for generating the sample data:
CREATE TABLE EMPLOYEE,DEPARTMENT INT,EMAIL Varchar)INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES --These are the duplicate rowsINSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES
We can see the duplicate rows in the above table.
DELETE e1 FROM EMPLOYEE e1, EMPLOYEE e2 WHERE e1.name = e2.name AND e1.id > e2.id
The SQL query above will delete the rows, where the name fields are duplicated, and it will retain only those unique rows in which the names are unique and the ID fields are the lowest. That is, rows with IDs 5 and 6 are deleted, whereas rows with IDs 1 and 2 are retained.
Q50 Name The Operator Which Is Used In The Query For Pattern Matching
LIKE operator is used for pattern matching, and it can be used as -.
For example- select * from students where studentname like a%
_ it matches exactly one character.For example- select * from student where studentname like abc_
Apart from this SQL Interview Questions Blog, if you want to get trained from professionals on this technology, you can opt for structured training from edureka!
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Possible Questions By Chief Technology Officer
- Doyou have anyentrepreneurial experience that you want to talk about?
- What are the areas you think you need more development in?
- Why did you leave your last company and why this company?
- What has been some of the key learnings from your previous stint
- What was your proudest moment so far in the Data Science journey?