Why is my CASE expression non-deterministic?

Question

I am trying to create a persisted computed column using CASE expression:

ALTER TABLE dbo.Calendar ADD PreviousDate AS 
case WHEN [Date]>\'20100101\' THEN          


        

Answer 1

Apparently it is very picky about data types. Try doing this:

ALTER TABLE dbo.Calendar ADD PreviousDate AS 
case WHEN [Date ]> Convert(DateTime, '20100101', 101) THEN  [Date]
    ELSE Convert(DateTime, NULL, 101)
    END PERSISTED