在CLOB XML DB2上选择

Question

I have this data as CLOB field in DB2. I am converting the data to char using cast:

SELECT CAST(CLOBColumn as VARCHAR(32000))
FROM Schema.MyTable;

Here is how the result XML comes out from the above:

<TreeList TreeNo="ABC">
    <Tree ErrorCode="INVALID_TREE" ErrorDescription="Tree doesn’t exist." TreeID="123456"/>
    <Tree ErrorCode="INVALID_TREE" ErrorDescription="Tree doesn’t exist." TreeID="1234567"/>
</TreeList>

And this is how I expect my output

|TreeNo | TreeID  |   ErrorCode  | ErrorDescription
|ABC    | 123456  | INVALID_TREE | Tree doesn’t exist
|ABC    | 1234567 | INVALID_TREE | Tree doesn’t exist

How do I achieve this?

Answer 1

You need to use the XMLTABLE function which allows to map XML data to a table. You can pass in XML-typed data and it works if you directly parse the CLOB to XML. The SELECT would look like the following (you get the idea):

SELECT x.*
FROM schema.mytable, XMLTABLE(
    '$CLOBColumn/TreeList'
    COLUMNS 
    TreeNo VARCHAR(10) PATH '@TreeNo',
    TreeID INT PATH 'Tree[@TreeID]',
    ...
) AS x
;