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Remove Duplicates With Window Functions
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Remove Duplicates With Window Functions

MediumSQL · PostgreSQL

Problem

How do you handle duplicate records in a dataset using SQL? Write a query using window functions to identify and remove duplicates.

Use dataset_records and retain the earliest record for each duplicate set. The query should remove later duplicates and return the identifiers of the records removed.

Output

  1. One row per removed duplicate
  2. Column: removed_record_id
  3. Sort by removed_record_id ascending

Schema

dataset_records
ColumnTypeDescription
record_idPKINTUnique dataset record identifier
source_systemVARCHAR(40)System that supplied the record
external_idVARCHAR(40)Identifier assigned by the source system
event_typeVARCHAR(30)Type of dataset event
event_dateDATEBusiness date of the event
amountNUMERIC(10,2)Amount associated with the event
loaded_atTIMESTAMPTimestamp when the record entered the dataset
Tablesdataset_records
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