Dataford
Interview QuestionsInterview GuidesExperiencesMock InterviewsPricing
Get started

SQL Running Totals and Moving Averages

MediumSQL · PostgreSQL00:00
Practice interviewer
In session
5 left
00:00

Your question is SQL Running Totals and Moving Averages. Start with the requirements and the two tables on the right.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

You need to log in / sign up to run or submit.

Problem

Cambridge Mobile Telematics uses telematics event data to monitor driver risk in its safety analytics products. Write a PostgreSQL query that reports confirmed harsh-braking activity for each driver.

Requirements

  1. Aggregate confirmed harsh-braking events by driver and event date.
  2. Calculate a cumulative running total per driver, ordered chronologically.
  3. Calculate the average daily harsh-braking count over the current date and preceding 29 calendar days for each driver.
  4. Return results ordered by driver and event date. Exclude non-harsh-braking and non-confirmed events.

Schema

drivers
ColumnTypeDescription
driver_idPKINTEGERUnique driver identifier
driver_nameVARCHAR(100)Driver display name
regionVARCHAR(50)Operating region
driving_events
ColumnTypeDescription
event_idPKINTEGERUnique telematics event identifier
driver_idINTEGERDriver associated with the event
event_dateDATEDate on which the event occurred
event_typeVARCHAR(40)Type of driving event
event_statusVARCHAR(20)Review status of the event
Tablesdriversdriving_events
Your solutionPostgreSQL
You need to log in / sign up to run or submit.
Run a query to see results