我在hive中有一个表，其中的数据来自sap系统。此表包含以下列和数据：

+======================================================================+
|document_number | year | cost_centre | vendor_account_number | amount | 
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |                       |  123.5 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  25.96 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |                       |  586   |
+----------------------------------------------------------------------+

如上所示，值 vendor_account_number 列只存在于一行中，我想将它带到所有其他行中。
预期产出如下：

+======================================================================+
|document_number | year | cost_centre | vendor_account_number | amount | 
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  123.5 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  25.96 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  586   |
+----------------------------------------------------------------------+

为了实现这一点，我在hive中编写了以下cte

with non_blank_account_no as(
  select document_number, vendor_account_number
  from my_table
  where vendor_account_number != ''
)

然后进行自左外连接，如下所示：

select 
    a.document_number, a.year, 
    a.cost_centre, a.amount,
    b.vendor_account_number
from my_table a
left outer join non_blank_account_no b on a.document_number = b.document_number
where a.document_number = ' '

但是我得到了如下所示的重复输出

+======================================================================+
|document_number | year | cost_centre | vendor_account_number | amount | 
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  123.5 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  25.96 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  586   |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  123.5 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  25.96 |
+----------------------------------------------------------------------+
|       1        | 2016 |     XZ10    |      1234567890       |  586   |
+----------------------------------------------------------------------+

有人能帮我理解我的Hive查询有什么问题吗？