Deleting a set of entries based on sum of entries in the set

Hi,

I have a table that has columns date, code and amount. There are many other columns but they are irrelevant. Each line in this table belongs to a group. Each group has a code in the corresponding column. That is, each line has own date and amount, but the code is the same for the group. I would like to delete all the groups of lines if the sum of their amount equals to zero. How can that be done?