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N033-M4 Tier 3 · Intermediate · medium ecommerce · Brightlane

Return the quarter number and the hour-of-day for the timestamp `'2024-08-22 14:30:00'` in a single row

Part of Date Truncation and Extraction in SQL

The problem

Brightlane's financial reporting system records both the fiscal quarter and the submission hour for each transaction.

Write a query to return the quarter number and the hour-of-day for the timestamp '2024-08-22 14:30:00' in a single row.

Output:

  • A single row with columns quarter_number and hour_of_day, each containing a number.
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
  EXTRACT(
    quarter
    FROM
      '2024-08-22 14:30:00'::TIMESTAMP
  ) AS quarter_number,
  EXTRACT(
    HOUR
    FROM
      '2024-08-22 14:30:00'::TIMESTAMP
  ) AS hour_of_day

The shape

EXTRACT pulls one numeric component at a time, so producing two components from the same datetime means writing two extractions side by side. The August 22 timestamp yields 3 for the quarter and 14 for the hour. The financial reporting system gets both dimensions of the transaction in a single row.

Clause by clause

  • SELECT EXTRACT(quarter FROM '2024-08-22 14:30:00'::timestamp) AS quarter_number returns the fiscal quarter the timestamp falls in. PostgreSQL maps months 1–3 to quarter 1, months 4–6 to quarter 2, and so on, so August (month 8) lands in quarter 3.
  • EXTRACT(hour FROM '2024-08-22 14:30:00'::timestamp) AS hour_of_day returns the hour portion of the clock time. The minutes and seconds are discarded by the extraction; only the hour component, 14, comes through.
  • There is no FROM because both expressions evaluate against the same literal directly.

The trap

The quarter index is fixed to the calendar year, not to a custom fiscal year. EXTRACT(quarter FROM ...) always treats January through March as quarter 1. An organization whose fiscal year starts in any month other than January will need to derive its quarter index from the month number with arithmetic; the quarter field will silently report the wrong quarter for every row otherwise. The standard quarter the function returns is correct only when the reporting calendar matches the Gregorian calendar.

You practiced two EXTRACT calls in one statement — pull two different numeric components from the same source datetime.

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