Re: fetch updated columns in 'before update' trigger

[Jon Beyer]

> "Access the updated columns in a 'before update' trigger" contradicts itself---the result of an update can't be accessed before the update has occurred. So I can't make sense of the question.


The following statement would be updating col_a and col_b:

UPDATE my_table SET col_a = '1', col_b = '2'

In the trigger, I want a list of columns that are being updated, i.e. col_a and col_b.



> Nor do I understand "...updating the trigger..."---Triggers aren't updateable.

I supposed 'delete and recreate updated trigger' would have been more precise. My trigger could exhaustively make sure that none of the columns that I effectively want to make read-only are updated, but I don't want to have to modify my trigger every time I add a column. I want to basically say "is the list of updated columns == to just the one column that should still be able to be updated"


> Nor do I understand "...add more columns"---are you building an Update statement, or what?

I may add more columns in the future. The trigger isn't listening for addition of columns. But I don't want to need to rewrite my trigger whenever I add a new column to the database.