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SQL for Top Customer Spend

MediumSQL · PostgreSQL00:00
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Your question is SQL for Top Customer Spend. Start with the requirements and the two tables on the right.

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Problem

EPAM India's order analytics dashboard needs to identify its highest-value customers. As of 2024-04-01, write a PostgreSQL query that finds the three customers with the greatest spending during the preceding three calendar months, from 2024-01-01 inclusive through 2024-04-01 exclusive.

Requirements

  1. Join orders to order_items using order_id.
  2. Calculate spending as quantity * unit_price for each item.
  3. Aggregate spending by customer, exclude orders outside the date range and customers with no customer ID, then return the top three customers in descending spending order.

Schema

orders
ColumnTypeDescription
order_idPKINTEGERUnique order identifier
customer_idINTEGERIdentifier of the customer who placed the order
customer_nameVARCHAR(100)Customer display name captured on the order
order_dateDATEDate on which the order was placed
order_items
ColumnTypeDescription
order_item_idPKINTEGERUnique order item identifier
order_idINTEGERIdentifier of the associated order
quantityINTEGERNumber of units in the item row
unit_priceNUMERIC(10,2)Price per unit for the item row
Tablesordersorder_items
Your solutionPostgreSQL
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