Question about how not to insert the same row twice

Question

hello everyone
i have two tables
table employee_list
employee_id
employee_name
employee_num
employee_date
and table employee_form
employee_id
employee_name
employee_num
employee_date
table employee_form should contain the exact data like employee_list .
if there are missing data i'm inserting it to table employee_form_miss(missing).
now i have a probelm cause the compair between the two table,take place
more then just one time.now if there are still missing data i don't want that to table employee_form_miss will insert the same data that already exist in this table.
i've been thinking about constraints table employee_form_miss(employee_id
employee_name
employee_num
employee_date).
but i think it will be a wird way to handle this because i will do an insert
and then what rollback? or delete?
please help me how to manage this
thanks in advance.

Answer 1

hello everyone
i have two tables
table employee_list
employee_id
employee_name
employee_num
employee_date
and table employee_form
employee_id
employee_name
employee_num
employee_date
i'm using an embedded sql in cobol program
DECLARE AA CURSOR FOR
select a.employee_name ,a.employee_num,a.employee_date
from employee_list a
WHERE a.employee_date = :employee-date
and NOT EXISTS
(select null from employee_form
WHERE employee_name =a.employee_name and
employee_num = a.employee_num and
employee_date = a.employee_date )
i'm doing open and fetch to the cursor.
and loop over the sqlerrd(3) result in order to insert them to the employee_form_miss table
insert into employee_form_miss (employee_name,employee_num,employee_date)
values (:employee-name,:employee-num,:employee-date)
the employee_id in table employee_form_miss there is a trigger which
Increment the sequence by 1 for each row that we insert.
so my question was that if i'm doing a constraint, so still i have to do
an insert and then if there is a constraint to do rollback or delete
from duplicate row. is there a better way to manage this ?
thank you