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Top Devices Per Plant Query
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Top Devices Per Plant Query

MediumSQL · PostgreSQL

Problem

Becton Dickinson operations wants a quarterly view of which medical devices are produced in the highest volumes at each manufacturing plant. Assume the report runs on January 15, 2026, so the last quarter is October 1 through December 31, 2025.

Write a PostgreSQL query that returns the top three devices by total produced units for each plant.

Requirements

  1. Include only production runs dated from 2025-10-01 through 2025-12-31.
  2. Include only runs with status = 'Completed'.
  3. Aggregate units_produced by plant and device, treating NULL units as zero.
  4. Rank devices independently within each plant and return at most three per plant.
  5. Break production-volume ties alphabetically by device name, and sort the final output by plant name and rank.

Schema

plants
ColumnTypeDescription
plant_idPKINTEGERManufacturing plant identifier
plant_nameVARCHAR(100)Manufacturing plant name
cityVARCHAR(100)Plant city
regionVARCHAR(50)Operating region
devices
ColumnTypeDescription
device_idPKINTEGERMedical device identifier
device_nameVARCHAR(150)BD medical device name
device_categoryVARCHAR(100)Device category
production_runs
ColumnTypeDescription
run_idPKINTEGERProduction run identifier
plant_idINTEGERReferences plants.plant_id
device_idINTEGERReferences devices.device_id
production_dateDATEDate of the production run
units_producedINTEGERNumber of devices produced
statusVARCHAR(20)Production run status
Tablesplantsdevicesproduction_runs
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