SELECT sale_date,
       CASE WEEKDAY(sale_date)
           WHEN 0 THEN 'Monday'
           WHEN 1 THEN 'Tuesday'
           WHEN 2 THEN 'Wednesday'
           WHEN 3 THEN 'Thursday'
           WHEN 4 THEN 'Friday'
           WHEN 5 THEN 'Saturday'
           WHEN 6 THEN 'Sunday'
       END AS day_name
FROM sales;