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SQL Duplicate Record Detection

MediumSQL · PostgreSQL00:00
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Your question is SQL Duplicate Record Detection. Start with the requirements and the three tables on the right.

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Problem

American Institutes for Research needs to identify potentially duplicated assessment submissions before QA validation and reporting. Treat submissions as duplicates when the same participant completed the same assessment on the same administration date.

Write a PostgreSQL query that returns every submission belonging to a duplicate group.

Requirements

  1. Group submissions by participant_id, assessment_id, and administration_date.
  2. Keep only groups containing more than one submission.
  3. Return participant and assessment details, the duplicate count, and each affected submission ID, ordered consistently for review.

Schema

participants
ColumnTypeDescription
participant_idPKINTUnique participant identifier
full_nameVARCHAR(100)Participant's full name
assessments
ColumnTypeDescription
assessment_idPKINTUnique assessment identifier
assessment_codeVARCHAR(30)Short AIR assessment code
assessment_nameVARCHAR(150)Assessment title
submissions
ColumnTypeDescription
submission_idPKINTUnique submission identifier
participant_idINTReferences participants.participant_id
assessment_idINTReferences assessments.assessment_id
administration_dateDATEDate on which the assessment was administered
statusVARCHAR(20)Current submission QA status
reviewer_noteTEXTOptional note from QA review
Tablesparticipantsassessmentssubmissions
Your solutionPostgreSQL
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