Re: trigger with dynamic column name

[Peter Brawley]

SQL with variable column names needs PREPARE, which MySQL doesn't support in Triggers.

The table design isn't optimal---if a date needs to be edited, a difference of a day can require the value to be moved to a different column. Nonsensical. Cumbersome date logic like that belongs in reports, not in table designs.

If you're stuck with that design for the moment, you'll need to write a conditional block to cover all 12 months of the year, eg ...

declare mo tinyint unsigned;
set mo = month( new.order_date );
case mo
  when 1 then ...
...
end case;