Oracle使用（+）进行左外部联接

Question

I have this query using outer left self join and it displays what I would expect:

SELECT c.date, u.user_id from order_detail_trans c
LEFT OUTER JOIN order_detail_trans u
ON u.trans_id = c.trans_id
AND u.trans_type = 'UPDATE DETAIL'

I am joining a table to itself because I want one of my columns (user_id) to be populated only for those rows with trans_type of 'UPDATE DETAIL'... but still need to display rows from this table where this is not the trans type. The above query seems to do the trick. I get records with both trans_types, and those with 'UPDATE DETAIL' as trans_type display user_id

I need this to work with the Oracle (+) syntax, here is what I have going off of this source -- https://chartio.com/resources/tutorials/left-and-right-joins-using-the-plus-sign-in-oracle/#performing-outer-joins-using-the-symbol :

SELECT c.date, u.user_id from order_detail_trans c, order_detail_trans u
WHERE u.trans_id(+) = c.trans_id
AND u.trans_type = 'UPDATE DETAIL'

But this doesn't display rows with trans_type of anything other than 'UPDATE DETAIL'

What would be the correct way of re-writing the first query with (+) syntax to render the same results?

Answer 1

Need to include the (+) Operator on the Condition with the Literal

The older outer join approach requires that you include the (+) operator for the condition on the literal.

Just put your "retro" mental cap on and return back to the 90's. :)

Here is how it should look with this approach:

SELECT
    c
.DATE,
 u.user_id
FROM
    order_detail_trans c,
    order_detail_trans u
WHERE
    u.trans_id (+) = c.trans_id
    AND   u.trans_type (+) = 'UPDATE DETAIL'

Here is an example with the tables, emp and dept :

SCOTT@db>SELECT
  2      d.deptno,
  3      e.job
  4  FROM
  5      dept d
  6      LEFT OUTER JOIN emp e ON d.deptno = e.deptno
  7      and e.job = 'CLERK'
  8  GROUP BY
  9      d.deptno,
 10      e.job
 11  ORDER BY
 12      1,
 13      2;
  DEPTNO JOB     
      10 CLERK   
      20 CLERK   
      30 CLERK   
      40         


SCOTT@db>SELECT
  2      d.deptno,
  3      e.job
  4  FROM
  5      dept d,
  6      emp e
  7  WHERE
  8      d.deptno = e.deptno (+)
  9   AND e.job (+) = 'CLERK'
 10  GROUP BY
 11      d.deptno,
 12      e.job;
  DEPTNO JOB     
      20 CLERK   
      30 CLERK   
      10 CLERK   
      40    

Believe it or not, I believe most Oracle Applications shops just use this older outer join approach.