Oracle 递归

Question

Oracle递归

Answer 1

UPDATE T1
   SET T1.FY = (SELECT DECODE(SUM(FY), NULL, T1.FY, SUM(FY))
                   FROM T1 T2
                  WHERE T2.ID <> T1.ID
                    AND CONNECT_BY_ISLEAF = 1
                  START WITH T2.ID = T1.ID
                 CONNECT BY PRIOR T2.ID = T2.PAR_ID);

Answer 2

查询就用下面这个就可以。
SELECT T1.*,
       (SELECT DECODE(SUM(FY), NULL, T1.FY, SUM(FY))
          FROM T1 T2
         WHERE CONNECT_BY_ISLEAF = 1
         START WITH T2.ID = T1.ID
        CONNECT BY PRIOR T2.ID = T2.PAR_ID) SUMFY
  FROM T1

Answer 3

UPDATE T1
   SET T1.FY = (SELECT DECODE(SUM(FY), NULL, T1.FY, SUM(FY))
                   FROM T1 T2
                  WHERE T2.ID <> T1.ID
                    AND CONNECT_BY_ISLEAF = 1
                  START WITH T2.ID = T1.ID
                 CONNECT BY PRIOR T2.ID = T2.PAR_ID);
真的是佩服呀，不好想