I have always (or at least intended to) treat NULL and empty strings separately in my SQL querying history. Now I have run across something that mystifies me (but probably shouldn't) that I would like an explanation for. Consider this bit o' code:[code="other"]DECLARE @ORDER CHAR(10)SET @ORDER= ( SELECT NULL)IF @ORDER <> '' PRINT 'Not an empty string'IF @ORDER IS NULL PRINT 'It is NULL'[/code]Run this and you will get:[i]It is NULL[/i]I was expecting: [i]Not an empty stringIt is NULL[/i]Why is NULL not passing the 'not an empty string' test? In other words, how does NULL = '' ? Is NULL cast to an empty string for this comparison?Hopefully my feeling mystified is just from not enough caffeine yet.
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