Question

可能重复：
Oracle: Updating a table column using ROWNUM in conjunction with ORDER BY clause

我有一个返回一组有序记录的查询，我想将结果集中每行的rownumber复制到记录本身的一个名为Sequence的特定字段中。

SELECT ROWNUM, ID
FROM (
    SELECT ID 
    FROM MYTABLE 
    WHERE PARENT = 1
    ORDER BY SEQUENCE ASC
)

我有每行的ID，以及我要放在rownum字段中的SEQUENCE。如何循环遍历此结果集并相应地更新表？

Answer 1

merge into mytable t
using (SELECT ROWNUM rn, ID
       FROM (
         SELECT ID 
         FROM MYTABLE 
         WHERE PARENT = 1
         ORDER BY SEQUENCE ASC
      )) S 
on (t.id=s.id)
when matched then update set
  t.sequence=s.rn

如果id不是唯一的，您可以肯定：

merge into mytable t
using (SELECT ROWNUM rn, rwd
       FROM (
         SELECT rowid rwd
         FROM MYTABLE 
         WHERE PARENT = 1
         ORDER BY SEQUENCE ASC
      )) S 
on (t.rowid=s.rwd)
when matched then update set
  t.sequence=s.rn

Answer 2

请尝试：

  merge into EMP_MASTER x
  using (
          SELECT ID, ROW_NUMBER() OVER(ORDER BY SEQUENCE) y
          FROM MYTABLE 
          WHERE PARENT = 1
         ) s on (s.ID=x.ID)
         when matched then update set
  x.sequence=s.y;

适用于唯一ID。

在oracle中使用行号更新字段

2 个答案: