Hi every one . I created this trigger , but i can insert just one row information on my table
for example when insert first time information and want to insert antoher information Db2 return error for trigger


create trigger dec_num
after insert on sales
For each row mode db2sql
UPDATE product
SET pro_qty = pro_qty -1
where pro_id = (select pro_id from sales)

Check below clause

REFERENCING OLD AS OLD_TAB
NEW AS NEW_TAB
FOR EACH ROW MODE DB2SQL
UPDATE product
SET pro_qty = pro_qty -1
where pro_id =NEW_TAB.pro_id

hi . i don't understand this code , because I'm beginner in database