Update Trigger taking much time in DB2 on AS/400 ?

I am newbie in DB2 and created the following Trigger, to update the EMP2 
table Hierarchy, whenever update query is run on that table, but whenver I 
run the update query, it takes much time, atleast 5 minutes, when table has 
only 5 records. I have created this trigger with the help of IBM Examples on 
Internet, don't know what am I missing, do I have to use both NEW and OLD 
Keywords or something else.

Please help me out.

Best Regards,

Luqman

Here is the trigger.

CREATE TRIGGER trg_employees_u_calchierarchy
AFTER UPDATE ON EMP2
REFERENCING NEW AS NEW_EMP
FOR EACH ROW MODE DB2SQL
UPDATE EMP2 X
set HIERARCHY=
(SELECT  B.Hierarchy|| '.'||TRIM(CHAR(A.empid))
FROM Emp2 A, EMP2 B
WHERE A.MGRID = B.EMPID
AND A.EMPID=X.EMPID)
WHERE X.EMPID=NEW_EMP.EMPID