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When combining the output of two sets, how does UNION and UNION all treat NULL values?
Rows that contain NULL values aren't returned because NULL values can't be compared.
NULLs represent unknown values and can't be compared. UNION and UNION ALL will return an error if sets contain NULLs.
A NULL in one set is treated as being equal to a NULL in another set.
There are employee and customer query result sets, both of which containID(int) and country/region(nvarchar(20)) columns. Someone wants to return a list of countries/regions that appear in both result sets. Which set operator should they use?
EXCEPT
INTERSECT
OUTER APPLY
What type of result does the APPLY operator return?
Table-valued
Scalar
Aggregate
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