Null Value error

Question

Hi,
select decode(user_id,null ,'noname') from users
where name = 'JOHN'
in the users table , i dont have column with john . If i try the select statement then im getting null value which is correct, i m trying to use nvl,decode function so that i can add a value to it if it is null .
mean if there is no JOHn then it should it say noname.

Answer 1

You didn't have the right parameters going in your decode statement.
select decode(dummy,null, 'A', dummy) from dual;
Read as: Decode value in dummy, if it is null, put the value A, otherwise, put the value dummy.
select decode(user_id,null ,'noname', user_id) from users where name = 'JOHN'
Read as: Decode value in user_id, if it is null, put value noname, otherwise put user_id.
Or use nvl:
select nvl(user_id, 'noname') from users where name = 'JOHN'
read: if user_id is null, put the value 'noname', otherwise put value user_id.