Break into multiple rows based on date range of a single row

Question

I have a table which captures appointments, some are single day appointments and some are multi day appointments, so the data looks like

AppointmentId   Star         


        

Answer 1

Clearly a Calendar/Tally table would be the way to go as SqlZim illustrated (+1), however you can use an ad-hoc tally table with a CROSS APPLY.

Example

Select A.AppointmentId   
      ,StartDate = B.D  
      ,EndDate   = B.D
 From  YourTable A
 Cross Apply (
                Select Top (DateDiff(DD,A.StartDate,A.EndDate)+1) D=DateAdd(DD,-1+Row_Number() Over (Order By Number),A.StartDate) 
                 From  master..spt_values
             ) B

Returns

AppointmentId   StartDate   EndDate
9               2017-04-12  2017-04-12
10              2017-05-01  2017-05-01
10              2017-05-02  2017-05-02
10              2017-05-03  2017-05-03
11              2017-06-01  2017-06-01