Can you dynamically convert a text string into a column name?

I’m working on an SQL statement for DB2/400 (OS release V5R3). I have
several history tables each with an effective from timestamp (EFFFROMTS)
and effective thru timestamp (EFFTHRUTS). The purpose of my script is
to compare two rows (within the same table) and report the column name,
old value and new value, when a difference is found.

I feel I’m close with the script found below but, I can’t figure a
way to convert the value of COLUMN_NAME into a usable column name.

Is there a function available to convert a string into a column name?
My attempt of:

AND NOT T3.(T1.COLUMN_NAME) = T2.(T1.COLUMN_NAME)

does not work, but I think it gives you an idea of what I’m trying to
accomplish.

If this is not going to work, does anyone have another approached I
might try?

Thanks
Allen

SELECT T1.COLUMN_NAME
, CAST(T2.(T1.COLUMN_NAME) AS CHAR(30)) AS OLD_VALUE
, CAST(T3.(T1.COLUMN_NAME) AS CHAR(30)) AS NEW_VALUE ,
T3.EFFFROMTS

FROM SYSIBM.SQLCOLUMNS T1
INNER JOIN (SELECT * FROM EMPLOYEE
WHERE EMPNUM = :PARM_EMPNUM
AND EFFFROMTS BETWEEN :PARM_FROMTS
AND :PARM_THRUTS
ORDER BY EFFFROMTS) T2
INNER JOIN (SELECT * FROM EMPLOYEE
WHERE EMPNUM = :PARM_EMPNUM
AND EFFFROMTS BETWEEN :PARM_FROMTS
AND :PARM_THRUTS
ORDER BY EFFFROMTS) T3 ON RRN(T3) = (RRN(T2) + 1) AND
NOT T3.(T1.COLUMN_NAME) = T2.(T1.COLUMN_NAME)
WHERE T1.TABLE_SCHEM = :PARM_SCHEMA
AND T1.TABLE_NAME = 'EMPLOYEE' AND NOT T1.COLUMN_NAME IN
('EFFFROMTS', 'EFFTHRUTS') ;