Trigger to add multiple rows

Question

Hi
I have a Table with the following columns :Country,Province,City,Emp_no,Salary(table1)
I need to add all the salaries where Country,Province and City match and write this to a record in table2 with fields Country,Province,City,Total_Salaries(table2).
Any thoughts,

Answer 1

Sorry, I missed a little logic in the trigger. Assuming that you have previously populated table 2 with the summarized data, using something like
INSERT INTO table2
SELECT year,country,province,city,SUM(salary) total_salary
FROM table1
GROUP BY year,country,province,city;Then the following trigger should maintain the sums. Since you do not provide any information on how you are determining the year, I am assuming a year column in both tables.
CREATE TRIGGER updt2
BEFORE INSERT OR UPDATE OF table1
FOR EACH ROW
BEGIN
   IF :new.salary <> :old.salary THEN
      IF INSERTING THEN
         UPDATE table2
         SET total_salaries = total_salaries + :new.salary
         WHERE year := :new.year and
               country = :new.country and
               province = :new.province and
               city = :new.city;
         IF SQL%NOTFOUND THEN
            INSERT INTO table2 (year,country,province,city,total_salary)
            VALUES(:new.year,:new.country,:new.province,:new.city,:new.salary);
         END IF;
      ELSE
         UPDATE table2
         SET total_salaries = total_salaries + (:new.salary - :old.salary)
         WHERE year = :new.year and
               country = :new.country and
               province = :new.province and
               city = :new.city;
      END IF;
   END IF;
END;This should update table2 with the entire new salary if you are inserting a record, or the difference between the new and old salaries if you are updating a record. If there is a chance that the salary field could be null, you will need to account for that by using NVL function on all occurences.
John