Total Order Count — Aggregate Functions in SQL

The problem

Brightlane's operations team is building a weekly capacity report and needs a baseline order-volume figure.

Write a query to return the total number of orders the platform has processed in a single column named order_count.

Assumptions:

The orders table contains every order Brightlane has processed.
Every row in orders represents one order; the count is simply the row count.

Output:

A single row with one column, order_count, containing the total order count.

Schema · ecommerce 5 tables

categories

id integer

name text

parent_id? integer

products

id integer

name text

category_id integer

price numeric

stock_qty integer

attributes? jsonb

order_items

id integer

order_id integer

product_id integer

quantity integer

unit_price numeric

customers

id integer

name text

email text

city? text

country text

created_at timestamptz

is_active boolean

orders

id integer

customer_id integer

ordered_at timestamptz

status text

total_amount numeric

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Solution query

SELECT
  COUNT(*) AS order_count
FROM
  orders

The shape

COUNT(*) collapses every row of the orders table down to a single number — the total count of orders Brightlane has processed. An aggregate query always returns exactly one row of summary numbers, regardless of how many rows live in the source table.

Clause by clause

SELECT COUNT(*) is the aggregate. The * means "every row," so PostgreSQL walks the table, counts rows as it goes, and returns one number. The result row has one column whether the underlying table has zero, three, or three million rows. For this dataset, the count is 200.
AS order_count labels that single number as the domain quantity. Without it, the column would come back as count — PostgreSQL's default name for the result of COUNT. The alias makes the result self-documenting: anyone reading the column header knows what was counted.
FROM orders is what COUNT(*) reads from. Aggregates always need to know which set of rows to collapse, and the FROM clause provides that set.

You practiced collapsing an entire table to a single number with COUNT(*). The recurring shape: when the question is "how many rows," COUNT(*) reads every row's existence — column values are irrelevant.

Return the total number of orders the platform has processed in a single column named `order_count`

The shape

Clause by clause

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