Question

Sometimes I get a dash in output but I was told it’s not a null, so what is it?

select title, order#, STATE
from customers C, ORDERITEMS O, books b
where b.ISBN=O.ISBN (+)
order by title

CUSTOMERS:
Column Name Data Type   Nullable    Default Primary Key
CUSTOMER#   NUMBER(4,0) No  -   1
LASTNAME    VARCHAR2(10)    Yes -   -
FIRSTNAME   VARCHAR2(10)    Yes -   -
ADDRESS VARCHAR2(20)    Yes -   -
CITY    VARCHAR2(12)    Yes -   -
STATE   VARCHAR2(2) Yes -   -
ZIP VARCHAR2(5) Yes -   -
REFERRED    NUMBER(4,0) Yes -   - 

Answer 1

if you select ‘-‘ from dual, the output will be “-“.

If this is not the answer you are looking for, consider posting your query and maybe the DDL of the table in question.

I agree with user490735, it looks like his link has the answer. Also, ANSI join syntax is mucn easier (at least for me) to read.

The dash appears to be a place holder for null columns in the outer join. As a long shot, if the default value of the nullable columns is actually ‘-‘ (I don’t think it is) then you will get the dash in your query results.