‬‎ <column name> ‪is‬‎ ‪not‬‎ ‪valid‬‎ ‪in‬‎ ‪the‬‎ ‪context‬‎ ‪where‬‎ ‪it‬‎ ‪is‬‎ ‪used‬‎.‪‬‎ - db2

Question

I've been at this Create Trigger for a while...
I'm using IBM Data Studio 4.1.3 while making this Trigger. At first I had problems with ending statements with ';' but on the IBM website it says to use 'x' and it works.
My main problem, however, wondering why I get this message:
‬‪‬‎"‪N.ITEMNAME"‬‎ ‪is‬‎ ‪not‬‎ ‪valid‬‎ ‪in‬‎ ‪the‬‎ ‪context‬‎ ‪where‬‎ ‪it‬‎ ‪is‬‎ ‪used‬‎.‪‬‎.‪‬‎ ‪SQLCODE‬‎=‪‬‎-‪206‬‎,‪‬‎ ‪SQLSTATE‬‎=‪42703‬‎,‪‬‎ ‪DRIVER‬‎=‪3‬‎.‪69‬‎.‪56
This also applies to all the others: o.itemid, o.quantity, and n.quantity. I found this out when switching/swapping the names around each other.
The editor is telling me that it has no errors in the statement but when executing, problems arise.
-- <ScriptOptions statementTerminator="x" />
CREATE TRIGGER DB2ADMIN.SUPPLIES_I
AFTER UPDATE OF QUANTITY ON DB2ADMIN.SUPPLIES
REFERENCING NEW TABLE AS n
OLD TABLE AS o
FOR EACH ROW MODE DB2SQL NOT SECURED
BEGIN ATOMIC
INSERT INTO db2admin.tran_log VALUES (USER, CURRENT TIMESTAMP || ' ' || n.itemname || ' ( ' || o.itemid || ' ) from ' || CHAR(o.quantity) || ' to ' || CHAR(n.quantity));
END

Answer 1

Remove the TABLE word from the CREATE TRIGGER statement:
CREATE TRIGGER DB2ADMIN.SUPPLIES_I
AFTER UPDATE OF QUANTITY ON DB2ADMIN.SUPPLIES
REFERENCING NEW AS n
OLD AS o
FOR EACH ROW MODE DB2SQL NOT SECURED
BEGIN ATOMIC
INSERT INTO db2admin.tran_log VALUES (USER, CURRENT TIMESTAMP || ' ' || n.itemname || ' ( ' || o.itemid || ' ) from ' || CHAR(o.quantity) || ' to ' || CHAR(n.quantity));
END
You can't reference a table transition variable in the way you try. Imagine, that we build the new table as below.
It's possible:
with n(i) as (values 1, 2, 3)
select i
from n;
It's not possible, and you get the same error message:
with n(i) as (values 1, 2, 3)
values (n.i);
Alternative solution with a FOR EACH STATEMENT trigger
If you your table have a key (one or more columns), and it doesn't include the updated column QUANTITY:
CREATE TRIGGER DB2ADMIN.SUPPLIES_I2
AFTER UPDATE OF QUANTITY ON DB2ADMIN.SUPPLIES
REFERENCING NEW TABLE AS n
OLD TABLE AS o
FOR EACH STATEMENT
INSERT INTO db2admin.tran_log
SELECT USER, CURRENT TIMESTAMP || ' ' || n.itemname || ' ( ' || o.itemid || ' ) from ' || CHAR(o.quantity) || ' to ' || CHAR(n.quantity)
FROM n, o
WHERE n.<key>=o.<key>