(+)= "plus equal" operator in SQL statement

Question

I have the following sql statement in php. What does "(+)=" plus-equal operator mean in an SQL statement? e.g.

<?php

$query = "SELECT * FROM multimedia multi, titles title where title.id(+)=multi.title";

?>

Answer 1

This is old Oracle syntax for a left outer join. It is better written as:

SELECT *
FROM multimedia multi left outer join
     titles title
     on title.id = multi.title;

Here is documentation on the subject.

Answer 2

That's an Oracle style Outer Join. The equivalent ANSI join is:

select *
  from multimedia multi
  left join titles title
    on title.id = multi.title