American Express Data Engineering Manager Interview Questions and Answers

Q1. Implement lag() and lead() without using lag() or lead()
Ans. 
Implement lag() and lead() functions without using lag() or lead()
• To implement lag(), shift the values in the array by one position to the right

• To implement lead(), shift the values in the array by one position to the left

• For example, to implement lag() on [1, 2, 3, 4], you can shift the values to get [null, 1, 2, 3]

• For lead(), you can shift the values to get [2, 3, 4, null]
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Q2. How will you go about optimising a query?
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Optimising a query involves identifying bottlenecks and improving efficiency.
• Identify slow-performing queries using tools like query execution plans.

• Optimize database indexes to speed up query performance.

• Limit the number of columns and rows returned in the query.

• Avoid using SELECT * and instead specify only the necessary columns.

• Use appropriate data types and avoid unnecessary data conversions.

• Consider denormalizing d...read more
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Q3. If the 3rd position in a string contains 'b' replace it with 'v'
Ans. 
Replace 'b' with 'v' in the 3rd position of each string in an array
• Iterate through each string in the array

• Check if the 3rd position contains 'b'

• If yes, replace 'b' with 'v'
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Q1. SQL case study for data
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Q2. Find nth salary
Ans. 
To find the nth salary in a dataset
• Sort the dataset in descending order based on salary

• Remove duplicates if necessary

• Return the salary at index n-1
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Topics were, DSA, SQL, PL/SQL, Data Augmentation

Customer churn classification using a classification ML model

Q1. Write a pseudo code for Bubble sort
Ans. 
Bubble sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order.
• Start with the first element and compare it with the next element, swapping if necessary

• Repeat this process for each pair of adjacent elements in the array until the entire array is sorted

• Continue this process for each element in the array until no more swaps are ne
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Q2. What is an API
Ans. 
An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate with each other.
• APIs define the methods for requesting and receiving data between software applications

• APIs can be used to access data from external sources, such as social media platforms or weather services

• Examples of APIs include the Twitter API, Google Maps API, and Spotify API
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Q1. Tell me about yourself
Ans. 
I am a data analyst with a strong background in statistics and data visualization.
• Graduated with a degree in Statistics

• Proficient in programming languages like Python and R

• Experience in analyzing large datasets and creating data visualizations

• Strong problem-solving skills and attention to detail
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Q2. Salaray compensation how much
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