I have a question about this fiddle: <>https://dbfiddle.uk?rdbms=sqlserver_2019&fiddle=5fb4c089af3d52e645aade8970793767 Is it ever possible to get -1 as the result of this query? I think no, right because potato can be either null or not null and the case covers both scenario? sql server 11 Sincerely,
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You are correct. The CASE conditional expression can evaluate to either 1 or 0, never to a NULL. The encapsulating ISNULL function will always see a concrete value, `1` or `0`, and so will never return `-1`. If you explain what you are trying to achieve with this code that doesn't seem to work for you, we may be able to offer some advice.