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对prior的理解可以是:prior 用在那一列的前面,那么就对那一列进行递归。例如:下面这个树(10是8的子节点)
Null
1
2 3
4 7 8 9
10
select level,familyid,childid from family1 start with childid=3 connect by prior familyid = childid; (这个就对familyid字段进行递归)
LEVEL FAMILYID CHILDID
---------- ---------- ----------
1 1 3
2 1
select level,familyid,childid from family1 start with childid=3 connect by prior childid = familyid; (这个就对childid进行递归)
LEVEL FAMILYID CHILDID
---------- ---------- ----------
1 1 3
2 3 8
3 8 10
2 3 9
[ 本帖最后由 nikeachilles 于 2008-11-6 18:15 编辑 ] |
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