Automatically trimming length of string submitted to MySQL

Question

When I submit a form field to a mySQL database is there a way to set the database to automatically discard any data in excess of the data field length?

I know I can

Answer 1

You mean you want to set this in a data definition script for example when creating a table? According to the documentation you can't do this. Perhaps you could use a trigger to handle data before it is inserted? Something like this (I can not garantuee that the code below actually works):

CREATE TRIGGER chopdata BEFORE INSERT ON mytable
  FOR EACH ROW BEGIN
    NEW.myfield = SELECT SUBSTRING(NEW.myfield,1,20)
  END;

Else you can chop out the maximum length by using substring straight in your query/procedure:

SELECT SUBSTRING('your very long string goes here',1,20);