I'm believe many of people confuse null = null is equal null is null or not ? , which method should be, how about performance or something elase ,
however This topic we'll prove oracle treat the null value together
Considerate the easier example :
CHATCHAI_K> select sysdate from dual where null=null
no row selected
CHATCHAI_K> select sysdate from dual null is null
sysdate
-
31-OCT-10
from example it prove oracle NULL is not equal to NULL, but in some database vendor such as Sybase null is equal to null , therefore when you migrate database from one to another , your application may retrieve a wrong result that is not database processing wrong but it is just work difference that you need to understand !
Cheer !
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