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SQL Random Generator and Dedup
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SQL Random Generator and Dedup

MediumSQL · PostgreSQL

Problem

Given a function that returns 0 or 1 randomly, create a random number generator; then explain how you would delete duplicates in an SQL table.

For the SQL portion, treat rows with identical event attributes as duplicates and retain the row with the smallest trade_id. The query should remove duplicates and return the IDs of the deleted rows.

Output

  1. One row per deleted duplicate, with the column duplicate_trade_id
  2. Include only rows removed by the operation
  3. Sort by duplicate_trade_id ascending

Schema

trade_events
ColumnTypeDescription
trade_idPKBIGINTUnique identifier for the trade event
account_idVARCHAR(32)Trading account identifier
event_timeTIMESTAMPTime at which the event occurred
symbolVARCHAR(16)Security ticker symbol
sideVARCHAR(16)Trade action
quantityNUMERIC(18,4)Number of units in the event
priceNUMERIC(18,4)Execution price per unit
Tablestrade_events
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