3+表上的Oracle LEFT OUTER JOIN-（+）语法与ANSI语法

Question

Scenario: I need to convert an existing query using (+) outer join syntax to ANSI syntax. Reason : One of the JOINS requires an OR operand, which is not allowed with the (+) operator, but is allowed with LEFT OUTER JOIN. (At least I'm assuming this is correct.)

Goal of the Query: Table D contains that name of two hierarchies, BB and Commercial. Simple joins through these tables will return 19 Positions and their respective hierarchy. I need to see ALL positions with the appropriate hierarchy if valid, else a NULL value.

(+) Syntax Query - working correctly:

select a.userid, a.firstname, a.lastname, b.name PositionName, d.name Hierarchy

from cs_participant a, cs_position b, cs_positionrelation c, cs_positionrelationtype d

where a.payeeseq = b.payeeseq
and b.ruleelementownerseq = c.childpositionseq(+)
and c.positionrelationtypeseq = d.datatypeseq(+)
and b.removedate = to_date('01/01/2200','dd/mm/yyyy')
and b.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy')
and c.removedate(+) = to_date('01/01/2200','dd/mm/yyyy')
and d.removedate(+) = to_date('01/01/2200','dd/mm/yyyy')
and a.removedate = to_date('01/01/2200','dd/mm/yyyy')
and a.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy')

Result Example:

My Attempt with ANSI Syntax:

select a.firstname, a.lastname, b.name, d.name as "Hierarchy"
from cs_participant a, cs_position b

left outer join cs_positionrelation c on c.parentpositionseq = b.ruleelementownerseq 
or c.childpositionseq = b.ruleelementownerseq (--This is the OR clause
that I cannot execute in the (+) syntax query)

left outer join cs_positionrelationtype d on d.datatypeseq = c.positionrelationtypeseq

where a.payeeseq = b.payeeseq
and b.removedate = to_date('01/01/2200','dd/mm/yyyy')
and b.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy')
and a.removedate = to_date('01/01/2200','dd/mm/yyyy')
and c.removedate = to_date('01/01/2200','dd/mm/yyyy')
and c.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy')
and d.removedate = to_date('01/01/2200','dd/mm/yyyy')

ANSI Query Results:

This query returns ONLY the Positions that are assigned to a hierarchy. I need to see ALL positions, with or without a hierarchy assignment, which are currently being excluded from the results.

Answer 1

You have two date literals as outer join conditions in your first query, but you leave them in the where clause in the second query. To change the syntax properly, those criteria need to be left as part of the join criteria. It's also bad form to combine the two join syntax (ie having comma seperated tables and the join keyword in the same query).

Below is the first query properly adapted to SQL-99 syntax:

SELECT a.userid,
       a.firstname,
       a.lastname,
       b.name AS positionname,
       d.name AS hierarchy
FROM   cs_participant a
       JOIN cs_position b ON a.payeeseq = b.payeeseq
       LEFT JOIN cs_positionrelation c
          ON     b.ruleelementownerseq = c.childpositionseq
             AND c.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       LEFT JOIN cs_positionrelationtype d
          ON     c.positionrelationtypeseq = d.datatypeseq
             AND d.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
WHERE      b.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND b.effectiveenddate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND a.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND a.effectiveenddate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')

Once that's done, adapting it to join on either column is trivial:

SELECT a.userid,
       a.firstname,
       a.lastname,
       b.name AS positionname,
       d.name AS hierarchy
FROM   cs_participant a
       JOIN cs_position b ON a.payeeseq = b.payeeseq
       LEFT JOIN cs_positionrelation c
          ON     (   c.parentpositionseq = b.ruleelementownerseq
                  OR c.childpositionseq = b.ruleelementownerseq)
             AND c.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       LEFT JOIN cs_positionrelationtype d
          ON     c.positionrelationtypeseq = d.datatypeseq
             AND d.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
WHERE      b.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND b.effectiveenddate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND a.removedate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')
       AND a.effectiveenddate = TO_DATE ('01/01/2200', 'dd/mm/yyyy')

Answer 2

(Posting my comment as answer in case this was what you wanted)

OR is same as a UNION. In oracle syntax, you can do

SELECT * FROM TABLE1, TABLE2 WHERE B1=C1(+) 
union 
SELECT * FROM TABLE1, TABLE2 WHERE B2=C2(+)

This is the same as -

SELECT * FROM TABLE1 LEFT JOIN TABLE2 ON (B1=C1 OR B2=C2)

(Maybe use UNION ALL if at all possible)

Union is how a FULL OUTER JOIN was possible in oracle syntax.

Answer 3

The problem is your date filters in where clause:

and d.removedate = to_date('01/01/2200','dd/mm/yyyy')

You need to move this condition to the table's join clause, or deal with null values using NVL (I suppose you are using Oracle). Try this for example:

select a.firstname,
        a.lastname,
        b.name as "PositionName",
        d.name as "Hierarchy"
  from cs_participant a
      , cs_position b
  left outer join cs_positionrelation c
    on c.parentpositionseq = b.ruleelementownerseq 
    or c.childpositionseq = b.ruleelementownerseq
  left outer join cs_positionrelationtype d
    on d.datatypeseq = c.positionrelationtypeseq
   and d.removedate = c.removedate --MOVED FROM WHERE
 where a.payeeseq = b.payeeseq
   and b.removedate = to_date('01/01/2200','dd/mm/yyyy')
   and b.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy')
   and a.removedate = to_date('01/01/2200','dd/mm/yyyy')
   and c.removedate = to_date('01/01/2200','dd/mm/yyyy')
   and c.effectiveenddate = to_date('01/01/2200','dd/mm/yyyy');

Or just add the NVL function in your condition:

and nvl(d.removedate,to_date('01/01/2200','dd/mm/yyyy')) = to_date('01/01/2200','dd/mm/yyyy')