Dataford
Interview QuestionsInterview GuidesExperiencesMock InterviewsPricing
Get started
Find Duplicates in SQL
00:00
5 left

Find Duplicates in SQL

EasySQL · PostgreSQL

Problem

Ryan Specialty needs to identify duplicate policy records in a staging table before loading data into the core system. Write a SQL query to find every policy_number that appears more than once.

Requirements

  1. Return each duplicated policy_number
  2. Include how many times each duplicated value appears
  3. Sort the result by duplicate count descending, then policy_number ascending

Schema

policy_staging
ColumnTypeDescription
record_idPKINTUnique row identifier
policy_numberVARCHAR(50)Policy identifier from the source feed
insured_nameVARCHAR(255)Named insured on the policy
effective_dateDATEPolicy effective date
premium_amountDECIMAL(12,2)Written premium for the record
Tablespolicy_staging
Interviewer

Your question is Find Duplicates in SQL. Start with the requirements and the one table in the Question tab.

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.
CodePostgreSQL
You need to log in / sign up to run or submit.Ln 1
Run your query to see results here.