impact of storing the null values in a table

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impact of storing the null values in a table

SQL*

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March 3, 2010 at 1:09 am

#139112

Hi,
what is the impact of storing the null values in a table. If there is any issue, what is the alternative for the null.
🙂

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Elliott Whitlow SSC Guru Points: 102402 More actions · Answer 1

An impact would be that you can't test for an a NULL with = NULL you have to use IS NULL. NULLs are usually excluded from most aggregates.

NULL values have their place, it typically means "I don't know/care". It is useful where you don't want to designate some value to indicate "unknown".. For three state logic you can have yes, no, and I don't know.

CEWII

SQL* SSCertifiable Points: 6638 More actions · Answer 2

hi,

thanks for ur response,

what is "three state logic"?

🙂

Bhuvnesh SSC Guru Points: 59351 More actions · Answer 3

dba-vb (3/3/2010)
what is the impact of storing the null values in a table

Read Below post

http://www.sqlservercentral.com/articles/Advanced+Querying/2829/

You will find "three state logic" Even more than that

-------Bhuvnesh----------
I work only to learn Sql Server...though my company pays me for getting their stuff done;-)

Jeff Moden SSC Guru Points: 1004407 More actions · Answer 4

dba-vb (3/5/2010)
hi,
thanks for ur response,
what is "three state logic"?

True, False, and "Unknown".

The real affect of having NULLs in a table is usually (not always) a thing called "Denormalization" and except for certain reporting tables, it's normally not a good thing.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

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