DB2 SQL - Filter non-xml, invalid xml data using XMLCAST(XMLQUERY (Xpath) function in case statement

Question

Need help in filtering bad xml data from the column which is blob format. Using the below query to achieve this and facing the below error.

Query: SELECT COLUMN1 AS NAME, CASE WHEN COLUMN2 = '' THEN XMLCAST( XMLQUERY( '$file/*:value' PASSING XMLPARSE( DOCUMENT TABLE."DATA" ) AS "file" ) AS VARCHAR(10)) ELSE COLUMN2 END AS INFO FROM TABLE

Error: [Code: -16110, SQL State: 2200M] XML syntax error. Expected to find "Comment or PI".. SQLCODE=-16110, SQLSTATE=2200M, DRIVER=4.22.29

Answer 1

There is no "safe" XMLPARSE function in Db2, but you may create it.

--#SET TERMINATOR @

-- Returns NULL on bad document
CREATE FUNCTION XMLPARSE_SAFE (P_DOC CLOB (1M))
RETURNS XML
CONTAINS SQL
DETERMINISTIC
NO EXTERNAL ACTION
BEGIN
    DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN END;
    RETURN XMLPARSE (DOCUMENT P_DOC);
END@

-- Usage
SELECT S, XMLPARSE_SAFE (S) AS DOC
FROM 
(
VALUES
  '<value>Not Eligible</value>'
, '<value>Not Eligible</alue>'
) T (S)@