Waht does (+) mean

Question

select * from   CIRC.COMPLAINT CM,  CIRC.CPT_CATEGORY_DTL CMCAT
where CM.TYPE_COMPLAINT        =  CMCAT.COMPLAINT_TYPE (+)I am sorry its dumb question but what does that mean (+) is it a join left outer join or right outer join ??? Is this same as outer join if not does it have any advantage over outer join

Answer 1

Hello! Varun!
The (+) is Oracle syntax for outer joins.
Your example:
select * from   CIRC.COMPLAINT CM,  CIRC.CPT_CATEGORY_DTL CMCAT
where CM.TYPE_COMPLAINT        =  CMCAT.COMPLAINT_TYPE (+)in ANSI syntax looks like that:
SELECT *
   FROM  CIRC.COMPLAINT CM
            LEFT OUTER JOIN CIRC.CPT_CATEGORY_DTL CMCAT
                    ON ( CM.TYPE_COMPLAINT = CMCAT.COMPLAINT_TYPE)Here is little example to clear things up:
Setup example:
CREATE TABLE tab_a(ID)
AS SELECT ROWNUM FROM dual CONNECT BY ROWNUM < 5;
CREATE TABLE tab_b(ID)
AS SELECT ROWNUM + 2 FROM dual CONNECT BY ROWNUM < 5;
Left outer join:
    -- Oracle Syntax:
    SELECT A.ID, b.ID
      FROM tab_a A,
           tab_b b
     WHERE A.ID = b.ID(+)
     ORDER BY a.ID;
    -- ANSI Syntax:
    SELECT A.ID, b.ID
      FROM tab_a A
           LEFT OUTER JOIN tab_b b
                ON (a.ID = b.ID)
     ORDER BY A.ID;
    -- Result:
    a_ID     b_ID
    1         <null>
    2         <null>
    3         3
    4         4 Right outer join:
    -- Oracle Syntax:       
    SELECT A.ID, b.ID
      FROM tab_a A,
           tab_b b
     WHERE A.ID(+) = b.ID
     ORDER BY A.ID;
    -- ANSI Syntax:
    SELECT A.ID, b.ID
      FROM tab_a A
           RIGHT OUTER JOIN tab_b b
                 ON (A.ID = b.ID)
     ORDER BY A.ID;
    -- Result:
    a_ID     b_ID
    3         3
    4         4
    <null>  6
    <null>  5                 Hope that helps.
Best regards,
Matt