Weekend Hours Solution

WITH hours_worked as (
  
SELECT
      emp_id,
  	   CASE 
       WHEN datepart(minute,TIMESTAMP) >= datepart(minute,lag(TIMESTAMP) OVER(PARTITION BY CAST(TIMESTAMP AS date),emp_id ORDER BY TIMESTAMP)) then datepart(hour,timestamp) - datepart(hour,lag(TIMESTAMP) OVER(PARTITION BY CAST(TIMESTAMP AS date),emp_id ORDER BY TIMESTAMP)) 
  	   ELSE datepart(hour,timestamp) - datepart(hour,lag(TIMESTAMP) OVER(PARTITION BY CAST(TIMESTAMP AS date),emp_id ORDER BY TIMESTAMP)) - 1
       END AS hours_worked
FROM   attendance
-- only weekends
WHERE  datepart(weekday,TIMESTAMP) IN(7,1)
)
SELECT
   emp_id,
      SUM(hours_worked) as hours_worked
FROM  hours_worked
GROUP BY emp_id
ORDER BY hours_worked desc