Techtree It Systems Linux System Administrator Interview Questions and Answers

Joins in SQL are used to combine data from two or more tables based on a related column.

• Inner join returns only the matching rows from both tables

• Left join returns all rows from the left table and matching rows from the right table

• Right join returns all rows from the right table and matching rows from the left table

• Full outer join returns all rows from both tables, with NULL values for non-matching rows

• Cross join retur...read more

Given an array of integers, find a contiguous subarray with a given sum.

• Use a sliding window approach to iterate through the array and keep track of the current sum.

• If the current sum exceeds the given sum, move the window's left endpoint forward.

• If the current sum is less than the given sum, move the window's right endpoint forward.

• If the current sum equals the given sum, return the subarray.

• Time complexity: O(n), Spa...read more

Check if a number is prime and optimize the code.

• Start by checking if the number is less than 2, in which case it is not prime.

• Iterate from 2 to the square root of the number and check if any of them divide the number evenly.

• If a divisor is found, the number is not prime. Otherwise, it is prime.

To optimise API calls in React, use asynchronous functions and caching techniques.

• Use async/await to handle API calls

• Implement caching to reduce network requests

• Use memoization to avoid unnecessary re-renders

• Consider using a state management library like Redux

• Use performance profiling tools like React DevTools