MYSQL: How to make NULL or empty data default to 0 during insert

Question

So this seems like it would be pretty straight forward and I swear I\'ve done this before, but for some reason it\'s just not working for me.

I am using MAMP

Answer 1

If you are explicitly setting the value to NULL in your insert, but want MySQL to replace the NULL with 0, one way to do that is to define the column to allow NULL in the CREATE TABLE statement, and then replace the NULL with a TRIGGER.

Something like this:

CREATE TABLE `listings` (
  `ListingID` int(11) NOT NULL,
  `BathsFull` int(6) NULL DEFAULT 0,
  PRIMARY KEY (`ListingID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

delimiter $$

create trigger tr_b_ins_listings before insert on listings for each row
begin
  set new.BathsFull = coalesce(new.BathsFull,0);
end $$

delimiter ;

Try it for yourself in this SQL Fiddle