oracle 求每列的最大值

Question

test 表中有 num1、num2、num3 3个字段

第一列、第二列、第三列
1 1 1

2 -1 2

3 1 -1

-1 2 1

1 3 2

求每列 -1 之前的最大值

结果是：3、1、2

Answer 1

ok了. 查询每列值为 -1的 前一排最近值, 如果该列中没有-1.则返回0.
select t1.c1, t2.c2, t3.c3
from (select nvl (min(c1),0) c1
from test
where rowid =

    (select max(rowid)
              from test
             where rowid < (select rowid from test where c1 = -1)) order by c1) t1,

   (select nvl (min(c2),0) c2
      from test
     where rowid = 

    (select max(rowid)
              from test
             where rowid < (select rowid from test where c2 = -1)) order by c2) t2,

   (select nvl (min(c3),0) c3
      from test
     where rowid = 

    (select max(rowid)
              from test
             where rowid < (select rowid from test where c3 = -1)) order by c3) t3