When i enter quantity it should display total

There is a menu contains fields: Item_id, Description, Rate, Quantity and Total.

=> Item_id contains 5 items.
=> rate and discription can be changed any time.

now Question is when i enter quantity it should display total (formula)
and suppose i choose 5 items and i enter quantities it shoud give me the total bill (Summary)

Which triggers I can use to accomplish this task. and suppose I change the rate and discription what will happen?

[B]Question asked by visitor Manikumar[/b]

no need to write triggers for this purpose.

Triggers are written to implement some business logic .

U can write a procedure for the purpose.

you should use "before insert" trigger the statement you need to use would be like,

:new.total := :new.rate * :new.quantity;


But in ur case there is no need to use trigger itself. The following insert statement is sufficient,

insert into item_table(Item_id, Description, Rate, Quantity,Total)
values (lv_Item_id, lv_Description, lv_Rate, lv_Quantity ,lv_Rate * lv_Quantity)


Hope this helps

Thats wha i have suggested.