Hi,
I have some doubts regarding NULL values. Can any one help me in clearing my doubts.
I have created a table:-
create table suppliers
(
supplier_id number,
supplier_name varchar2(10)
);
Next, I will insert two records into this table.
insert into suppliers (supplier_id, supplier_name )
values ( 10565, null );
insert into suppliers (supplier_id, supplier_name )
values ( 10566, '' );
Q 1) Can any one tell which is the null value, whether it is supplier_name having 10565 or 10506.
2) Empty String is null value
or
NULL is null value
3) Because of this Null value doubts i have another doubt . How many null values can be their in a column if that column is defined as UNIQUE?
Regards,
Naveen