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Top Merchants and Segments

MediumSQL · PostgreSQL00:00
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Your question is Top Merchants and Segments. Start with the requirements and the three tables on the right.

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Problem

How would you use SQL to identify the top-performing merchants and customer segments at DoorDash USA?

Use completed orders only and exclude customers without a defined segment. Return the top three merchants and top three customer segments, ranked separately by total order value.

Output

  1. One row per qualifying merchant or customer segment.
  2. Columns: entity_type, entity_name, order_count, total_order_value, and performance_rank.
  3. Include ties only when they fall within the top three ranks. Sort by entity type, rank, and entity name.

Schema

orders
ColumnTypeDescription
order_idPKINTUnique order identifier
merchant_idINTMerchant associated with the order
customer_idINTCustomer who placed the order
order_statusVARCHAR(20)Current order status
order_valueNUMERIC(10,2)Order value in US dollars
order_dateDATEDate the order was placed
merchants
ColumnTypeDescription
merchant_idPKINTUnique merchant identifier
merchant_nameVARCHAR(100)Merchant display name
marketVARCHAR(50)Primary US market
customers
ColumnTypeDescription
customer_idPKINTUnique customer identifier
customer_nameVARCHAR(100)Customer display name
customer_segmentVARCHAR(30)Customer lifecycle or engagement segment
Tablesordersmerchantscustomers
Your solutionPostgreSQL
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