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SQL Extraction With Joins
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SQL Extraction With Joins

HardSQL · PostgreSQL

Problem

Write the SQL query to extract specific data, using joins, aggregations, and filtering.

Use the provided customer, order, order item, and product tables. Return completed orders from the first quarter of 2025, retaining monthly category totals that reach at least 100 in revenue.

Output

  1. One row per product category and qualifying month.
  2. Columns: category, month, revenue, order_count, prior_month_revenue, and revenue_change_pct.
  3. Sort by category, then month ascending.

Schema

customers
ColumnTypeDescription
customer_idPKINTCustomer identifier
customer_nameVARCHAR(100)Customer name
orders
ColumnTypeDescription
order_idPKINTOrder identifier
customer_idINTCustomer who placed the order
order_dateDATEOrder date
statusVARCHAR(20)Order status
order_items
ColumnTypeDescription
order_item_idPKINTOrder line identifier
order_idINTRelated order
product_idINTRelated product
quantityINTQuantity purchased
unit_priceNUMERIC(10,2)Price per unit at purchase
products
ColumnTypeDescription
product_idPKINTProduct identifier
product_nameVARCHAR(100)Product name
categoryVARCHAR(50)Product category
Tablescustomersordersorder_itemsproducts
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