把下面的mysql语法改为oracle; update temp_asset_table a join ( select x.id,@rownum :=@rownum + 1 AS 'row_num' from ( SELECT id from temp_asset_table where BATCH_ID=batchId and ASSET_TYPE = '100' order by row_num desc ) x,(SELECT @rownum := v_max_id_100) temp ) d on a.id=d.id set a.ASSET_NUMBER= d.row_num where a.ASSET_TYPE = '100' and a.BATCH_ID=batchId;

在 Oracle 中，可以使用以下语法来执行相同的操作：

UPDATE (
  SELECT a.ASSET_NUMBER, ROW_NUMBER() OVER (ORDER BY x.row_num DESC) AS row_num
  FROM temp_asset_table a
  JOIN (
    SELECT id, ROW_NUMBER() OVER (ORDER BY row_num DESC) AS row_num
    FROM (
      SELECT id, rownum AS row_num
      FROM (
        SELECT id, ROWNUM AS rownum
        FROM temp_asset_table
        WHERE BATCH_ID = batchId AND ASSET_TYPE = '100'
        ORDER BY row_num DESC
      )
    )
  ) x ON a.id = x.id
  WHERE a.ASSET_TYPE = '100' AND a.BATCH_ID = batchId
) SET ASSET_NUMBER = row_num;

其中，使用了 `ROW_NUMBER()` 函数来生成每条记录的行号，两个子查询分别用于生成 `id` 和 `row_num`，最终通过 `JOIN` 进行匹配，并在外层使用 `SET` 子句来更新 `ASSET_NUMBER` 字段。需要注意的是，在 Oracle 中，不能在 `JOIN` 子句中使用 `@rownum` 变量。