Value of NULL

[ashlee]

I want to know what is the value of NULL in oracle.Is this equal to zero, or is it equal to spaces or any junk value.

[sarunraj]

NULL is not equal to ZERO.
It just means that there is no value at all in that memory area / column / field.

Hope it helps,
Arun

[nnirmalkumar]

hi,

Its just a empty thing............ thts all

[ashlee]

I could understand that it is nothing but what is the value that gets stored in memory area of the column made as NULL. Will it be junk?

[madug]

hai
Null is not a Zero or any number ,it is a blank space

[caradoc]

Friends very nice discussion going around. Since NULL is blank as specified here in this discussion is it possible to compare two NULL. Will it give error?

[nagivijay]

The value of null is unkown..it means its not been initiated. So null never be considered as zero or anyvalue.In a table balnk space and zero both has a value. so null is considered as an unkown.

[sarunraj]

Hi,

NULL in Oracle means that there is no value in that memory area. It is not equal to 0.

see the folliwing SQL script..

SQL> select emp_id, emp_name, mobile from emp;

In this script, if the employee doesnt have any mobile number entered into the database, this query will return a NULL value (NO value) for the column Mobile.
Example output:

EMP_ID EMP_NAME MOBILE
------- ---------- --------
101 JOHN

In this case the MOBILE number of JOHN is not entered, so no value is retrieved for that field.

you can rewrite the SQL script as
SQL> select emp_id, emp_name, NVL(mobile, 'Not Entered');

In this Case the output will be
EMP_ID EMP_NAME MOBILE
------- ---------- --------
101 JOHN Not Entered

NVL( ) function checks whether the value is null or not. If the value is null, then it will return string mentioned.

Hope this clarifies....

Arun

[prem.ranjan]

Originally Posted by ashlee

I want to know what is the value of NULL in oracle.Is this equal to zero, or is it equal to spaces or any junk value.

NULL is nothing but a character data type with zero lenth string.

[psiva_exforsys]

In oracle NULL is not equal to any one (NULL or any number). In oracle NULL value stored in empty in database table. but internally it has some alpha numeric value.

Regards,
Siva.P
Bangalore