Compute total or average prices for products labelled "Oracle" using joins and aggregate functions.
It’s simply a nickname for queries that total, average, or otherwise measure the cost of products whose name contains “Oracle” in a PostgreSQL-based ecommerce schema.
You need Products
for the unit price, OrderItems
for quantities, and optionally Orders
or Customers
for filtering by dates or buyers.
Join Products
to OrderItems
, multiply price × quantity
, and sum the result.Use ILIKE '%oracle%'
to catch case variations.
COALESCE
in pricing queries?Missing or NULL prices break math. COALESCE(price,0)
guarantees arithmetic safety so totals don’t return NULL.
Group by the product id or name and divide the sum of revenue by the sum of quantities to get a true weighted average.
Add an index on Products.name
with LOWER(name)
for faster ILIKE searches.Keep price
in NUMERIC(12,2)
to avoid rounding errors.
Don’t forget the quantity multiplier—summing only prices under-counts revenue. Use JOIN
, not CROSS JOIN
, to prevent exploding row counts.
.
Add a discount
column or subquery and subtract it in the revenue expression, e.g., (price - discount) * quantity
.
Store historical prices in a separate table or use price
plus an effective_from
column, then join on date ranges.
NUMERIC
keeps exact decimal precision, avoiding rounding issues common with floating-point types.