I have a (SQL Server) table that contains 3 types of results: FLOAT, NVARCHAR(30), or DATETIME (3 separate columns). I want to ensure that for any given row, only one column has a result and the other columns are NULL. What is the simplest check constraint to achieve this?
Update: Sorry, data type snafu. Sadly I wasn't intending the result types indicated to be interpreted as SQL Server datatypes, just generic terms, fixed now.