SQL Server Dateadd-从选择查询中是否获取间隔？

Question

Depending on Frequency Range (nvarchar), which can be 'Weekly' or 'Monthly', I would like to use the result to set the interval of the dateadd function

SELECT rs.ScheduledStartDate, rs.ScheduledEndDate, rs.Frequency, rs.FreqRange, rs.LastCreated
FROM RosterSchedule rs
WHERE dateadd(case when rs.FreqRange = 'Weekly' Then day else month end), rs.Frequency, rs.LastCreated) = GETDATE()

Answer 1

Should possibly be something like

…
WHERE
  CASE
    WHEN rs.FreqRange = 'Weekly'  THEN DATEADD(WEEK,  rs.Frequency, rs.LastCreated)
    WHEN rs.FreqRange = 'Monthly' THEN DATEADD(MONTH, rs.Frequency, rs.LastCreated)
  END = today

Answer 2

I think reverse the order of the comparison:

WHERE CAST(GETDATE() AS DATE) = CASE
                                WHEN rs.FreqRange = 'Weekly' THEN DATEADD(Week, rs.Frequency, rs.lastcreated)
                                WHEN rs.FreqRange = 'Monthly' THEN  DATEADD(Month, rs.Frequency, rs.lastcreated)
                                ELSE '1/1/1900' -- Adjust this as needed
                                END