从DB2中的别名获取最大值

Question

I wanna searching for max value in my alias. this is my query

SELECT DISTINCT IPK.NIM,IPK.NAMA,IPK.IPK
FROM MAHASISWA M, PENILAIAN P, MATA_KULIAH MK, KRS K,
(SELECT M.NIM,M.NAMA, ROUND(SUM(P.ANGKA*MK.SKS)/SUM(MK.SKS),2) AS IPK
FROM MAHASISWA M, PENILAIAN P,MATA_KULIAH MK,KRS K
WHERE M.NIM=K.NIM AND MK.KODE_MK=K.KODE_MK AND K.NILAI=P.NILAI GROUP BY M.NIM,M.NAMA
) AS IPK
WHERE IPK.IPK=(SELECT MAX(IPK.IPK) FROM IPK);

But when I run it, it says DB2ADMIN.IPK was not found. How I can search it from my own alias in my query?

Answer 1

You should be able to do something like this:

SELECT DISTINCT IPK.NIM,IPK.NAMA,IPK.IPK
    FROM MAHASISWA M, PENILAIAN P, MATA_KULIAH MK, KRS K,
    (
        SELECT M.NIM,M.NAMA, ROUND(SUM(P.ANGKA*MK.SKS)/SUM(MK.SKS),2) AS IPK
           FROM MAHASISWA M, PENILAIAN P,MATA_KULIAH MK,KRS K
           WHERE M.NIM=K.NIM AND MK.KODE_MK=K.KODE_MK AND K.NILAI=P.NILAI 
           GROUP BY M.NIM,M.NAMA
           ORDER BY IPK DESC
           FETCH FIRST ROW ONLY               
    ) AS IPK;

This will cause the inner query to only return the maximum row.

Here is how to get the average IPK for each:

SELECT IPK.NIM,IPK.NAMA, AVG(IPK.IPK)
    FROM MAHASISWA M, PENILAIAN P, MATA_KULIAH MK, KRS K
    (
        SELECT M.NIM,M.NAMA, ROUND(SUM(P.ANGKA*MK.SKS)/SUM(MK.SKS),2) AS IPK
           FROM MAHASISWA M, PENILAIAN P,MATA_KULIAH MK,KRS K
           WHERE M.NIM=K.NIM AND MK.KODE_MK=K.KODE_MK AND K.NILAI=P.NILAI 
           GROUP BY M.NIM,M.NAMA

    ) AS IPK
    GROUP BY IPK.NIM,IPK.NAMA;