Question

I have been porting oracle selects, and I have been running across a lot of queries like so:

SELECT e.last_name,
       d.department_name
  FROM employees e,
      departments d
WHERE e.department_id(+) = d.department_id;

…and:

SELECT last_name, 
       d.department_id
  FROM employees e, 
       departments d
 WHERE e.department_id = d.department_id(+);

Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)?

Even better.. Is there a tool/script that will do this conversion for me (Preferred Free)? An optimizer of some sort? I have around 500 of these queries to port..

When was this standard phased out? Any info is appreciated.

Answer 1

The (+) is Oracle specific pre-ANSI-92 OUTER JOIN syntax, because ANSI-89 syntax doesn’t provide syntax for OUTER JOIN support.

Whether it is RIGHT or LEFT is determined by which table & column reference the notation is attached to. If it is specified next to a column associated with the first table in the FROM clause – it’s a RIGHT join. Otherwise, it’s a LEFT join. This a good reference for anyone needing to know the difference between JOINs.

First query re-written using ANSI-92 syntax:

    SELECT e.lastname,
           d.department_name
      FROM EMPLOYEES e
RIGHT JOIN DEPARTMENTS d ON d.departmentid = e.departmentid

Second query re-written using ANSI-92 syntax:

   SELECT e.lastname,
          d.department_name
     FROM EMPLOYEES e
LEFT JOIN DEPARTMENTS d ON d.departmentid = e.departmentid