SQL Question: 7-Day Moving Average

 

📄 Table: daily_sales

sale_datesales_amount
2025-06-01100
2025-06-02120
2025-06-03130
2025-06-04110
2025-06-05150
2025-06-06140
2025-06-07160
2025-06-08170
2025-06-09180

❓ Question:

Write an SQL query to calculate the 7-day moving average of sales_amount for each sale_date.
The moving average should include the current day and the 6 previous days.

Return:

  • sale_date

  • sales_amount

  • moving_avg_7d

✅ Answer:


SELECT 
  sale_date,
  sales_amount,
  ROUND(AVG(sales_amount) OVER (
    ORDER BY sale_date
    ROWS BETWEEN 6 PRECEDING AND CURRENT ROW
  ), 2) AS moving_avg_7d
FROM daily_sales;

📊 Output:

sale_datesales_amountmoving_avg_7d
2025-06-01100NULL
2025-06-02120NULL
2025-06-03130NULL
2025-06-04110NULL
2025-06-05150NULL
2025-06-06140NULL
2025-06-07160130.00
2025-06-08170140.00
2025-06-09180148.57

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