Oracle query with out using self join

Question

hi friends,
i have one table for exeample PERSTATUS
pk/fK STUDENT NUMBER SUBJECT MARKS STATUS
1 ACCOUNTS 15 RED
1 MATHS 35 YELLOW
1 SCINECE 45 GREEN
2 ACCOUNTS 55 BROWN
2 MATHS 35 YELLOW
2 SCINECE 45 GREEN
3 ACCOUNTS 15 RED
3 MATHS 35 YELLOW
3 SCINECE 45 GREEN
i want students how status is both red and yellow so i am using self join
i want students status is both red and yellow so i am using self join
SELECT PS.STUDENTNUMBER,PS.STATUS,PS.STATUS1 FROM PERSTATUS PS ,PERSTATUS PS1
WHERE PS.STUDENTNUMBER-PS1.STUDENTNUMER
PS.STATUS='RED' AND PS1.STAUTS='YELLOW'
i want students status is both RD and YELLOW AND GREEN so i am using self join( two self joinS}
SELECT PS.STUDENTNUMBER,PS.STATUS,PS.STATUS,PS2.STATUS FROM PERSTATUS PS ,PERSTATUS PS1,PERSTATUS PS2
WHERE PS.STUDENTNUMBER-PS1.STUDENTNUMER AND PS.STUDENTNUMBER-PS2.STUDENTNUMBER
PS.STATUS='RED' AND PS1.STAUTS='YELLOW' AND PS2.STAUTUS='GREEN'
if i require MORE STATUS then more self joins required, is there any alternative to achive this
and if results comes in multiple rows are accepted (since with the above query result will come in single row)
i tried to use group by (studentnumber,status) with status='red' and status='yellow'
but it is not possible could you povidet he solution

Answer 1

Hi,
Whenever you have a problem, please post CREATE TABLE and INSERT statements for your sample data, and the exact results you want from that data. Explain how you get those results from that data.
See the forum FAQ {message:id=9360002}
Here's an example of how to post the sample data:
CREATE TABLE     perstatus
(       studentnumber     NUMBER
,     subject          VARCHAR2 (10)
,     marks          NUMBER
,     status          VARCHAR2 (10)
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (1,           'ACCOUNTS', 15,       'RED');
INSERT INTO perstatus (studentnumber, subject  ,  marks, status)
       VALUES           (1,           'MATHS',        35,       'YELLOW');
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (1,           'SCINECE',  45,       'GREEN');
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (2,           'ACCOUNTS', 55,       'BROWN');
INSERT INTO perstatus (studentnumber, subject  ,  marks, status)
       VALUES           (2,           'MATHS',        35,       'YELLOW');
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (2,           'SCINECE',  45,       'GREEN');
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (3,           'ACCOUNTS', 15,       'RED');
INSERT INTO perstatus (studentnumber, subject  ,  marks, status)
       VALUES           (3,           'MATHS',        35,       'YELLOW');
INSERT INTO perstatus (studentnumber, subject,    marks, status)
       VALUES           (3,           'SCINECE',  45,       'GREEN');You were on the right track, thinking about GROUP BY. You're interested in something about the whole group of rows that has the same studentnumber. Looking at any individual row won't tell you if that row is part of the group you're interested in or not.
If you want to see information about the group as a whole, you can do the whole job with GROUP BY. In this case, studnetnumber is the only thing that an entire group has in common. If you wanted to see the studentnumbers that had both RED and YELLOW, that is:
STUDENTNUMBER
            1
            3here's one way you could do it:
SELECT       studentnumber
FROM       perstatus
WHERE       status     IN ('RED', 'YELLOW')
GROUP BY  studentnumber
HAVING       COUNT (DISTINCT status) = 2  -- That is, both RED and YELLOW
ORDER BY  studentnumber
;But say you wanted to see details about individuals in the group; for example, say we want to see all the columns for students that have all 3 of RED, YELLOW and GREEN, like this:
STUDENTNUMBER SUBJECT         MARKS STATUS
            1 SCINECE            45 GREEN
            1 ACCOUNTS           15 RED
            1 MATHS              35 YELLOW
            3 SCINECE            45 GREEN
            3 ACCOUNTS           15 RED
            3 MATHS              35 YELLOWWe used the aggregate COUNT function earlier, but aggregate functions require collapsing the results down to one row per group.
However, most of the aggregate functions, like COUNT, have analytic counterparts, that can give the same results without collapsing the result set. Here's one way to get the results above, using the analytic COUNT function:
WITH     got_cnt          AS
     SELECT  studentnumber, subject, marks, status
     ,     COUNT ( DISTINCT CASE
                               WHEN  status  IN ('RED', 'YELLOW', 'GREEN')
                         THEN  status
                           END
                ) OVER (PARTITION BY  studentnumber)     AS cnt
     FROM    perstatus
SELECT    studentnumber, subject, marks, status
FROM       got_cnt
WHERE       cnt  = 3
ORDER BY  studentnumber
,            status
;