Listagg alternative in db2

Question

My customer is using db2 database without listagg function, but I need to somehow aggregate the primary key information within one field.

Right now (for Oracle) I am using this as a part of bigger query:

SELECT LISTAGG(COLUMN_NAME || ':' || CONTENT, ',') 
WITHIN GROUP (ORDER BY COLUMN_NAME || ':' || CONTENT) 
FROM TABLE
WHERE ROW_IDENTIFIER_ID = I.REC_ID AND I.TABLE_RESULT_ID = T.REC_ID

It there an alternative way to get result of listagg function in db2 database before DB2 as of version 9.7 Fix Pack 4¹ ?

Version of my customer's database: Linux - Enterprise server edition 9.7, release number 08060107
I got it by executing these selects:

SELECT * FROM TABLE(SYSPROC.ENV_GET_INST_INFO()) AS SYSTEMINFO;
SELECT * FROM TABLE(SYSPROC.ENV_GET_PROD_INFO()) AS SYSTEMINFO;
SELECT * FROM TABLE(SYSPROC.ENV_GET_SYS_INFO()) AS SYSTEMINFO;

I admit I don't understand, how can it be 9.7, but there is not listagg function?! :confused:

I also did executed:

SELECT * FROM SYSCAT.FUNCTIONS

I got back this function list, but there are no functions like xmltext or xmlgroup mentioned in alternative solutions down in the answers:(. What neanderthal database is the customer using? Or am I missing something?

Thanks for the responses.

Solution

If your version of DB2 supports pureXML (that would be at least DB2 for LUW 9.1 and I believe DB2 9 for z/OS), in addition to what @PM77-1 suggested above, you could use the XMLAGG function:

select xmlserialize(
  xmlagg(
    xmlconcat(
      xmltext(column_name),
      xmltext(':'),
      xmltext(content),
      xmltext(',')
    )
  ) as varchar(10000)
) 
from 
  yourtable 
...

Comments

[PM 77-1]

See if this workaround fits your needs.

[WarrenT]

Which DB2 server are you using: DB2 for i, LUW, or z/OS? And which version? Different DB2 platforms have different sets of built-in functions.

[Ondřej Vykouk]

Updated question with version info and function list.

[Clockwork-Muse]

I believe the XML extensions are optional, so they may not be installed. It's actually possible to do this with a recursive CTE (I've done this on an AS/400); unfortunately, I no longer have access to an instance to work against.

[Ondřej Vykouk]

PureXML support is surprisingly available, but functions are not listed in the select mentioned in the question. Together with workaround tip from PM 77-1 I managed to find a solution. Many thanks.

[mathiasrw]

"I managed to find a solution" Would be awesome if you could share the solution you found...