To update a table triggerred by another table's change

Hi Experts,

I need a solution to update a table, the update is triggerred by another table's change.

1)Where there is any change in table 1, it will checking whether the column of 'ack' has value of '0'.
2)if so, it need to trace to table 4 through table 2 and 3 by key.
3)update the column of 'affected' in table 4 by value '0', original is '1'.


May I know what tech I should use, may you give some detail code or examples.

Thanks and Regards,

Turbot