Define NULL - TechRepublic
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January 23, 2005 at 05:17 PM
jaqui

Define NULL

by jaqui . Updated 21 years, 5 months ago

since it came up in a discussion about sql.
I figured I would ask here.
what is the definition of NULL in sql,
c, c++,
java,
perl,
python.

and from where do you get this definition?

the discussion I’m pulling this querstion from:

In SQL, NULL means “unknown value”. How could you assert that two NULLs are equal?

which doesn’t make mathematical sense.
mathwise null is an empty result.
so setting the logic up using the math logic, null values are always equal.

What kind of mathematics you are speaking?
For example you have “infinity” where infinity is never
equal to infinity.
Same with null. Which is “unknown” or “undefined”
So if x is undefined and y is undefined you cannot
assume x=y – because if you assume this, then
they would not be undefined anymore.

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