Timestamping all rows of some tables on insert and update

I want to timestamp all the rows of some tables, whenever they are inserted or updated. Insertion is no problem - just set DEFAULT sysdate - but I'm stuck on updates. I thought I could use a trigger, but I get an error ORA-04091, that the table is mutating - basically I can't trigger an update in a row that is being updated. Fair enough, I guess, but how could I get around this?

You are getting an ORA-4091 table mutating because probably your UPDATE statement in the trigger is causing the entire table to mutate. This is a common mistake by novice programmers. Instead, the trigger approach is good; try writing:

  :new.timestamp_column := SYSDATE;

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