Data Manipulation (SQL/Python) Interview Questions

Showing 211–240 of 256 results

• StripeMedium·Data Scientist
  Design an idempotent SQL ETL for late data

  This question evaluates practical skills in idempotent ETL design, deduplication by natural keys, handling late-arriving and out-of-order records, upsert/merge strategies, and SQL-based aggregation for daily metrics.

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• StripeMedium·Data Scientist
  Design metrics and write SQL for a case

  This question evaluates the ability to define time‑bounded, attributable conversion metrics and to implement joins, aggregations, and diagnostic checks in SQL to measure marketing outreach impact.

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• StripeMedium·Software Engineer
  Design payment-to-invoice matcher with priorities

  This question evaluates parsing and data modeling skills, deterministic matching algorithms with prioritization and tie-breaking, handling monetary values as integer cents, and the ability to design comprehensive test suites for edge cases.

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• StripeMedium·Software Engineer
  Reconcile Monthly Bank-Account Balances Across Two Datasets

  Implement a reconciliation function that joins internal ledger balances with external bank statements for a target month, categorizing discrepancies while strictly distinguishing between missing records and zero balances.

  Data Manipulation (SQL/Python)Technical ScreenData ManipulationHash TableAccounting
• StripeMedium·Data Scientist
  Write SQL for snapshot features and labels

  This question evaluates proficiency in SQL-based feature engineering for time-series and user-event data, covering snapshotting, temporal joins, deduplication, windowed aggregations, distinct counting, and label construction in the Data Manipulation (SQL/Python) domain.

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• TTencentMedium·Data Scientist
  Compute per-player daily cumulative games with windows

  This question evaluates proficiency with SQL window functions, aggregation, date-aware grouping and joins for computing per-player daily counts and running totals, and it falls under Data Manipulation (SQL/Python) for Data Scientist roles, emphasizing practical application rather than purely theoretical concepts.

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• TeslaMedium·Machine Learning Engineer
  Compute nearest index within threshold after walking distances

  This question evaluates a candidate's proficiency in data manipulation, numerical computing with NumPy, spatial reasoning for Euclidean distance and interpolation along polylines, and designing time- and space-efficient algorithms for large-scale inputs.

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• TeslaMedium·Machine Learning Engineer
  Implement and vectorize NumPy Conv2D

  This question evaluates understanding of 2D convolution mechanics, multidimensional NumPy array manipulation, and the competency to optimize numerical computations for performance and memory.

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• TNThe New York TimesEasy·Data Analyst
  Write SQL for content-view analytics

  This question evaluates proficiency in SQL-based data manipulation and analytics, including aggregation, distinct counting, NULL handling, timestamp/hour extraction, device grouping, and row-level ordering, and is situated in the Data Manipulation (SQL/Python) domain.

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• TikTokMedium·Data Scientist
  Calculate Conversion Rate from Ad Clicks to Page Visits

  This question evaluates a candidate's competency in event-level data manipulation and metric computation using SQL or Python, including time-based aggregation, deduplication, and joining or windowing of event streams.

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• TikTokMedium·Data Scientist
  Calculate Day-7 Retention Rate from User Post Data

  This question evaluates a candidate's competency in SQL and Python data wrangling, emphasizing date arithmetic, window functions, grouping, and conditional aggregation for cohort and retention calculations.

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• TikTokMedium·Data Scientist
  Calculate User Registration Date and 7-Day Retention Rate

  This question evaluates the ability to perform time-based data manipulation and cohort retention analysis using SQL/Python, including deriving registration dates, aggregating posts within time windows, and computing retention metrics.

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• TikTokMedium·Data Scientist
  Calculate valid daily usage with gap constraints

  This question evaluates a candidate's ability to manipulate temporal intervals, including clipping to a specified day window, merging touching or overlapping segments, detecting gaps, and aggregating minute-level durations using SQL window functions and date/time arithmetic, and belongs to the Data Manipulation (SQL/Python) domain.

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• TikTokMedium·Data Scientist
  Compute 7-day rolling complaint/order ratio in SQL

  This question evaluates SQL data manipulation skills, specifically time-based aggregations, sliding window functions, joins to include entities with no events, and numeric casting within the Data Manipulation (SQL/Python) domain.

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• TikTokMedium·Data Scientist
  Compute and rank top bad advertisers

  This question evaluates proficiency in SQL data manipulation and analytics, including time-window filtering, JOINs, aggregation and deduplication, rate calculations, and window-function–based ranking.

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• TikTokMedium·Data Scientist
  Compute last-to-previous ad impression gaps

  This question evaluates proficiency in data manipulation and time-based analytics, covering SQL window functions, timestamp arithmetic, and grouping/ordering semantics within the Data Manipulation (SQL/Python) domain.

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• TikTokMedium·Data Engineer
  Debug a Hive Query for DAU

  This question evaluates proficiency in Hive/SQL query formulation, data partitioning and pruning, join and aggregation semantics, timestamp handling, and performance tuning for large-scale analytics.

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• TikTokMedium·Data Engineer
  Debug a Hive insert query

  This question evaluates a candidate's ability to debug Hive INSERT/SELECT operations, focusing on schema and column alignment, data types and casts, partition handling, file formats/SerDe, ACID/transactional constraints, and syntax or reserved keyword issues.

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• TikTokMedium·Software Engineer
  Discuss Python mutability, copying, and GIL

  This question evaluates understanding of Python mutability and copying semantics — including how mutable versus immutable objects affect function arguments and container behavior — and knowledge of the Global Interpreter Lock (GIL) and concurrency models.

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• TikTokMedium·Data Engineer
  Explain a SQL query result

  This question evaluates proficiency in SQL result-set interpretation and reasoning about joins, filters, aggregations, window functions, NULL handling, duplicate rows, and ordering within the Data Manipulation (SQL/Python) domain for a Data Engineer role.

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• TikTokEasy·Data Scientist
  Find top-paid employee per department

  This question evaluates a candidate's competency in SQL data manipulation, including aggregation, ranking, handling of duplicate and historical rows, tie semantics, and temporal data interpretation when determining the top-paid employee per department.

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• TikTokMedium·Data Scientist
  Identify Repeat Advertisers from Consecutive Weeks

  This question evaluates a candidate's proficiency in manipulating relational data to identify recurring entities across consecutive time periods, focusing on SQL/Python data manipulation and temporal comparison of records.

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• TikTokMedium·Data Scientist
  Investigating Correlation Between Ad Visits and Reports

  This question evaluates a data scientist's competency in operational analytics, including defining and aggregating metrics in SQL and applying causal reasoning to interpret correlations between ad exposures and user reports.

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• TikTokMedium·Data Scientist
  SQL Queries and Analysis on Bad Advertisers

  This question evaluates SQL query writing, metric definition and normalization, ranking/aggregation techniques, and analytical reasoning for identifying problematic advertisers.

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• TikTokEasy·Data Scientist
  Write SQL for TikTok Live creator metrics

  This question evaluates SQL data-manipulation competencies such as joins, aggregations, group-by and window functions, handling missing activity rows, date-range filtering, country partitioning, and deterministic tie-breaking for top-k metrics.

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• TikTokMedium·Data Scientist
  Write SQL for last-7-day metrics without windows

  This question evaluates proficiency in ANSI SQL data manipulation, including aggregation, de-duplication, date arithmetic, joins and subqueries, GROUP BY/HAVING usage, and cohort/retention and conversion calculations performed without window functions.

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• TikTokMedium·Software Engineer
  Write complex SQL for cohorts and retention

  This question evaluates advanced SQL and data-engineering competencies such as cohort and retention analysis, deduplication, timezone normalization, last-touch attribution, aggregate revenue calculations, and effective use of window functions in the Data Manipulation (SQL/Python) domain.

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• TFTools For HumanityEasy·Data Scientist
  Compute reply-based engagement metrics

  This question evaluates proficiency in data manipulation and analytics, emphasizing SQL/Python skills for temporal filtering, joins between posts and users, deduplication, aggregation (distinct counts), and percentage calculations used to compute reply-based engagement metrics.

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• TubiMedium·Data Scientist
  Compute daily net users from event logs

  This question evaluates SQL-based data manipulation skills focused on daily aggregation, cohort and retention calculations, deduplicating event records, and grouping metrics by device_platform.

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• TwitchMedium·Data Scientist
  Analyze Streaming Data with SQL for Monthly Trends

  This question evaluates proficiency in SQL time-series aggregation, date extraction and grouping across calendar months, join and conditional aggregation techniques, windowed month-over-month comparisons, and handling sparse or multi-year datasets; Category: Data Manipulation (SQL/Python); level: practical application.

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