Merge multiple rows into one row with sql
SELECT [Employee]
      ,[Year]
      ,[Period]
      ,[Activity]
      ,Sum([Day1]) as Day1
      ,Sum([Day2]) as Day2
      ,Sum([Day3]) as Day3
      ,Sum([Day4]) as Day4
      ,Sum([Day5]) as Day5
      ,Sum([Day6]) as Day6
      ,Sum([Day7]) as Day7
FROM [HoursAccounting]
where Employee = '1234'
group by Employee, [Year], Period, Activity;