" (+) = " operator in oracle sql in where clause

Question

while changing stored procedure i came across (+) = operator. I have read Oracle "(+)" Operator but seems like my problem is slightly different than one mentioned in that link. So, can anyone please help me understand statement like:

select ....
from emp, dept 
where emp.dept_id (+) = dept.dept_id

why would they use both + and = sign while using this condition? I would be thankful if someone will help me with example or link where i can read about such operators.

Answer 1

The (+)= operator refers to Oracle outer Joins wich simply extends the functionality of simple joins.

See the following link on this operator and this link on how to use it with example