Answer / ashu_deepu

2 NULL value can not b equal.

i just want to remind some imp. point about primary key.
d condition is
1) not null n
2) unique.
since 2 null value r unique dats why we require the 1st point of not null.

Answer / nhajare

Hi,
If you comapare null=null then it return 0 rows selected.
Check the result of this query...

select * from table_name where null=null;

Answer / sandeep kumar

select * from dual where null=null

no row return

Answer / naidu

NOT EQUAL AND AGAIN ANSWER IS NULL

Answer / kishore vakiti

select * from emp where null is null;

Answer / abhishek jaiswal

Decode will return true if we compare null to null value.
select decode(commission_pct,null,0) from employees

Answer / divi

Null is not equal to Null
Nor
Null is equal to Null

Answer / sureka

set serveroutput on;
DECLARE
D INTEGER :=NULL;
E INTEGER :=NULL;
BEGIN
IF (D = E) THEN
dbms_output.put_line('PASS');
ELSIF (D <> E) THEN
dbms_output.put_line('FAIL');
ELSE
dbms_output.put_line('NA');
END IF;
END;

will return NA

Answer / archana

begin
if null is null then
dbms_output.put_line('null');
else
dbms_output.put_line('not null');
end if
end;

now it will return null
it is recommended to use 'is' with null not ' ='

Answer / kuldeep123

DECLARE
v1 NUMBER;
v2 NUMBER;
BEGIN
IF v1 = v2
THEN
DBMS_OUTPUT.put_line ('Null comapred successfully');
ELSE
DBMS_OUTPUT.put_line ('oops u have to use ISNULL opeartor');
END IF;
END;


output : oops u have to use ISNULL opeartor

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