Rapid Repeat Card Charges

SQL practice question · Hard · Window Functions · Stripe, Paytm

A risk team wants to catch accidental double-billing. Only charges with status 'succeeded' matter; ignore every other status completely. A succeeded charge is a REPEAT when the previous succeeded charge with the same card_id, merchant_id and amount happened at most 10 minutes (600 seconds, inclusive) earlier. If two charges share the same timestamp, the one with the smaller charge_id counts as earlier. Return merchant_id, repeat_charges (number of repeat charges) and repeat_amount (sum of their amounts, ROUND to 2) for merchants with at least one repeat. Order by repeat_charges DESC, then merchant_id ASC.

Table: charges

Schema of charges
ColumnType
charge_idINTEGER
card_idTEXT
merchant_idTEXT
amountREAL
statusTEXT
charged_atTIMESTAMP
Sample rows of charges
charge_idcard_idmerchant_idamountstatuscharged_at
1card_Am_books499succeeded2026-02-01 10:00:00
2card_Am_books499succeeded2026-02-01 10:04:30
3card_Am_books499succeeded2026-02-01 10:20:00
4card_Bm_books120succeeded2026-02-01 11:00:00
5card_Bm_books120failed2026-02-01 11:01:00
6card_Bm_books120succeeded2026-02-01 11:02:00
7card_Cm_cabs80succeeded2026-02-01 09:00:00
8card_Cm_cabs85succeeded2026-02-01 09:03:00
Expected output on the sample data
merchant_idrepeat_chargesrepeat_amount
m_books2619
m_cabs180

Solve it in the live editor on this page — run on sample data, then submit against hidden tests.

‹ Orders per Delivery Partner with Unassigned · Payment Success Funnel by Method ›

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