What is the data type of Null?

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  • Jun 2nd, 2006

What is the Data Type of NULL?

In Tech Speack, NULL is a age old concept of nothing. This is not true in case of oracle. Oracle treats NULL as character value of length of 0.

So, the default data type of NULL is a character data type and to prove it, we create a view on a null column with an alias a, and then describe it to see the datatype and length of the string. Here is the code.....

create view myview
select null a from dual;

describe myview;

The describe command shows that the column a has a data type of a varchar2(0).

So the Answer is : Character Type


  • Jun 5th, 2006

Adding to Prev comments Also Null is and undefined Value its not = 0  ' '  (Space) , also if Value of null may not be equal to Null (null!= null)(its an unknow value or not defined value.

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Mohan Cherin

  • Jun 29th, 2006

Data type of NULL is any scalar variable i.e varchar2, char, number, date etc..

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Girish Bhatia

  • Jul 18th, 2006

Adding to Srinivas comments,

NULL has same datatype as the column, so if we make view with the following query

create view myview
select to_date(null) a from dual;

describe myview;

then datatype of it will be DATE, same way we can use to_number() function instead os to_date and see the results.

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Ritesh Ratna

  • Nov 3rd, 2006

NULL value is accepted by Fields that are Number Datatype also. So how can it be varchar. As varchar values can not be inserted in Field with Datatype  as Number.

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  • May 9th, 2007

Null may be any data type

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  • Feb 1st, 2008

A null value means the value is unav ailable, unassigned, unknown, or inapplicable. Therefore, you cannot test with = because a null cannot be equal or unequal to any value.

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  • Oct 1st, 2011

Null is the undefined value...
Null is never equal to zero..

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  • Mar 7th, 2012


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  • Jan 23rd, 2013

Null is not a value and not a string. It is unknown it is maximum in descending order and minimum value in ascending order.

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