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I'm just wondering what is faster in SQL (specifically SQL Server).
I could have a nullable column of type Date and compare that to NULL, or I could have a non-nullable Date column and a separate bit column, and compare the bit column to 1/0.
Is the comparison to the bit column going to be faster?
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If something is NULL it is undefined in T-SQL, so you cannot compare with it.
IS NULL and IS NOT NULL are predicates that can be used in conditional expressions. That means that they don't return a value themselves. Therefore, they can't be "cast" to a bit , or treated as a boolean.
You can't compare with NULL. You need is. null to test if something is a reference to the NULL object.
SQL Server IS NULL / IS NOT NULL Because the NULL value cannot be equal or unequal to any value, you cannot perform any comparison on this value by using operators such as '=' or '<>'.
In order to check that a column IS NULL SQL Server would actually just check a bit anyway. There is a NULL BITMAP stored for each row indicating whether each column contains a NULL or not.
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