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Detect Duplicate Charges in 5 Minutes
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Detect Duplicate Charges in 5 Minutes

MediumSQL · PostgreSQL

Problem

Given a table of credit card transactions, write a query to identify duplicate charges that occurred within 5 minutes of each other for the same account and amount.

Return each later charge together with the earlier charge it duplicates. Ignore rows with a missing account or amount.

Output

  1. One row per later charge identified as a duplicate
  2. Columns: transaction_id, account_id, amount, charge_time, previous_transaction_id, previous_charge_time
  3. Sort by account_id, charge_time, then transaction_id

Schema

credit_card_transactions
ColumnTypeDescription
transaction_idPKINTUnique transaction identifier
account_idVARCHAR(20)Credit card account identifier
amountDECIMAL(10,2)Charged transaction amount
charge_timeTIMESTAMPTZTimestamp when the charge occurred
Tablescredit_card_transactions
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