将SQL子查询转换为联接

Question

Hi I am trying to convert following sub query to just use joins but in the conversion there are some issue and the results are getting filtered incorrectly. Need help to figure out the problem or the correct query with join. The Sql with the sub query is working fine.

SELECT ev1.eventgender,ev1.distance,ev1.style FROM events ev1 
JOIN results re1 ON ev1.eventid = re1.eventid 
JOIN competitors cm1 on re1.competitornum = cm1.competitornum
WHERE cm1.countrycode = 'AUS'
AND ev1.eventid NOT  In (SELECT ev2.eventid FROM events ev2
                         JOIN results re2 ON ev2.eventid = re2.eventid 
                         JOIN Competitors cm2 ON re2.competitornum = cm2.competitornum 
                         WHERE cm2.countrycode = 'AUS'
                         AND re2.place IN (1,2,3))

I have tried the following query but the result is not correct

SELECT ev1.eventgender,ev1.distance,ev1.style FROM events ev1 
LEFT OUTER JOIN results re1 
     ON ev1.eventid = re1.eventid 
     AND re1.place Not in (1,2,3)
JOIN Competitors cm1 ON re1.competitornum = cm1.competitornum
AND cm1.countrycode = 'AUS'
WHERE ev1.eventid IS NOT NULL
ORDER by ev1.eventgender, ev1.style

Actual Result

Expected Result

Answer 1

Your subquery is not correlated, so you can move it directly to the from clause. Join it in using left outer join and check in the where clause for no matches:

SELECT ev1.eventgender, ev1.distance, ev1.style
FROM events ev1 JOIN
     results re1
     ON ev1.eventid = re1.eventid JOIN
     competitors cm1
     on re1.competitornum = cm1.competitornum left outer join
     (SELECT ev2.eventid
      FROM events ev2 JOIN
           results re2
           ON ev2.eventid = re2.eventid JOIN
           Competitors cm2
           ON re2.competitornum = cm2.competitornum 
      WHERE cm2.countrycode = 'AUS' AND re2.place IN (1,2,3)
     )
     on ev1.eventid = ev2.eventid
WHERE cm1.countrycode = 'AUS' and ev2.eventid is null