如何从 Oracle 数据库中提取嵌套的 XMLType 数据？

Question

我有以下 xml 数据存储在数据库的 xmltype 列中。

<TRNXS_DTL transactionSeq="1">
  <TRNX_ITEM sequence="1" name="ERROR_CODE" value="2009"/>
  <TRNX_ITEM sequence="2" name="ERROR_DESC" value="Data Not Found for given record id."/>
</TRNXS_DTL>

现在我尝试使用提取物查询数据库，如下所示：

  SELECT SRC_DSC_TXT as "TXT",   
  TYPE_CODE as "Code",   
  PID as "Participant ID",   
  SYS_ID as "System",   
  CHANEL as "Channel",   
  to_char(crt_ts,'MM/DD/YYYY HH24:MI:SS') as "Timestamp (MST)",   
  extract(TRX_DATA, '/TRNXS_DTL/TRNX_ITEM/text()') as "DETAILS"
  FROM PARTICIPANT_DATA,   
  WHERE SRC_VAL_TXT   =TYPE_CD;

但是当我运行以上查询时，我在“详细信息”列下得到空值，有什么想法吗？

Answer 1

您 XML 中的标签没有任何文字。它具有三个属性：序列、名称和值。所以，您的查询返回 NULL。

考虑以下示例。

create table myt(
type_code number,
trx_data xmltype
);

insert into myt values(101,
'<TRNXS_DTL transactionSeq="1">
  <TRNX_ITEM sequence="1" name="ERROR_CODE" value="2009"/>
  <TRNX_ITEM sequence="2" name="ERROR_DESC" value="Data Not Found for given record id."/>
</TRNXS_DTL>'
);

insert into myt values(102,
'<TRNXS_DTL transactionSeq="1">
  <TRNX_ITEM sequence="1" name="ERROR_CODE" value="2010">NNN</TRNX_ITEM>
  <TRNX_ITEM sequence="2" name="ERROR_DESC" value="Data Found for given record id.">OOO</TRNX_ITEM>
</TRNXS_DTL>'
);

SQL> select  * from myt;       

 TYPE_CODE TRX_DATA
---------- -------------------------------------------------------------------------------------------------------------
       101 <TRNXS_DTL transactionSeq="1">
             <TRNX_ITEM sequence="1" name="ERROR_CODE" value="2009"/>
             <TRNX_ITEM sequence="2" name="ERROR_DESC" value="Data Not Found for given record id."/>
           </TRNXS_DTL>

       102 <TRNXS_DTL transactionSeq="1">
             <TRNX_ITEM sequence="1" name="ERROR_CODE" value="2010">NNN</TRNX_ITEM>
             <TRNX_ITEM sequence="2" name="ERROR_DESC" value="Data Found for given record id.">OOO</TRNX_ITEM>
           </TRNXS_DTL>

for type_code 102 有 NNN 和 OOO 作为文本。

SQL> select type_code,
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM/text()').getStringVal() as "DETAILS"
from myt; 

 TYPE_CODE DETAILS
---------- -------------
       101
       102 NNNOOO

你可以看到，它连接了两个标签的文本。

如果您想要属性值，可以使用 @ 来指定属性。

SQL> select type_code,
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM/@value').getStringVal() as "DETAILS"
from myt; 

 TYPE_CODE DETAILS
---------- ------------------------------------------
       101 2009Data Not Found for given record id.
       102 2010Data Found for given record id.

同样，如您所见，文本是串联的。

如果你想让它们在单独的列中，你需要给出一个谓词来有条件地限制被选中的节点。

SQL> select type_code,
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM[@sequence="1"]/text()').getStringVal() as "DETAILS",
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM[@sequence="2"]/text()').getStringVal() as "DETAILS2"
from myt;

 TYPE_CODE DETAILS                  DETAILS2
---------- ------------------------ --------------
       101
       102 NNN                      OOO


SQL> select type_code,
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM[@sequence="1"]/@value').getStringVal() as "DETAILS",
extract(trx_data, '/TRNXS_DTL/TRNX_ITEM[@sequence="2"]/@value').getStringVal() as "DETAILS2"
from myt;

 TYPE_CODE DETAILS                  DETAILS2
---------- ------------------------ ------------------------------------------
       101 2009                     Data Not Found for given record id.
       102 2010                     Data Found for given record id.

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