Dataford
Dataford
Top 100
New this month
Updated daily · Last refresh Oct 31

New Interview Questions: September 2026

Questions added to the Dataford question bank in September 2026, ranked by how often they are asked in real interviews.

100questions
~38htotal time
255companies covered
Track your progressSign up free to work through all 100 questions and resume where you left off.
Start practicing free →
1
SQL & Data ManipulationStart here. 50 questions · ~1125 min
SQL Window Functions for TrendsMedium
Practice

Calculate three-day rolling user activity averages and classify behavior trends with SQL window functions.

null handlingData ManipulationAggregationsCCactus CommunicationsSStefaniniCCanadian Natural
Debug and Optimize Slow SQLMedium
Practice
Recently asked

Task A reporting query at a commerce platform summarizes recent orders for active customers, but the production version is slow. Write a PostgreSQL query t...

database optimizationlarge datasetsdatabase queryingOOvivaAAmerican Cruise LinesCChildren's Cancer Research Group
Rolling Average with Window FunctionsMedium
Practice
Recently asked

Calculate daily sales and a date-based 30-day rolling average using PostgreSQL window functions.

Date FunctionsData ManipulationAggregationsTTeva PharmaceuticalsYochanaSSika
7-Day Rolling Average with Window FunctionsMedium
Practice
Recently asked

Calculate each user's 7-day rolling order volume average, including calendar days with no orders.

Window FunctionsDate FunctionsData ManipulationDDelivery HeroRRBC IncorporatedTTeya
More SQL & Data Manipulation questions with a free account
2
Coding50 questions · ~1125 min
Cosine Similarity From ScratchMedium
Practice
Recently asked

Compute cosine similarity for equal-length high-dimensional vectors using dot products and Euclidean norms.

function implementationArraysArray ManipulationCommonwealth Bank of AustraliaLLogicFFever
Reverse a Linked ListEasy
Practice
Recently asked

Reverse a singly linked list in place by rewiring each node's next pointer.

CodingLinked ListsfunctionsFortinetAccentureCity And County Of San Francisco
Longest Substring Without RepeatsMedium
Practice

Find the longest substring without duplicate characters using a sliding window and last-seen index map.

ArraysArray ManipulationAlgorithmsDeloitteQuinceApple
LRU Cache ImplementationHard
Practice
Recently asked

Implement an LRU cache with constant-time get and put operations using a hash map and doubly linked list.

cachingData Structureslru cacheHHebbiaDDisney+HotStarSnap
More Coding questions with a free account

Sign up to see every question

Create a free account to unlock this list and practice real interview questions.

Get my prep plan
The finish line: interview-readyComplete all 100 questions to finish this plan.