Having covered why nulls exist and how they can be created
explicitly and implicitly, let’s look at how NULLs behave by
looking at some specific examples. I previously showed that you can specify NULL explicitly, but what happens when
NULLs interact with non-NULLs:

SELECT NULL + 1;
 ?column?
----------
   (null)
 
SELECT NULL || 'a';
 ?column?
----------
 (null)
 
SELECT 'b' || NULL;
 ?column?
----------
 (null)

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