MySQL - Can you retrieve the default value of a column?

Question

I was looking at creating a TRIGGER that will set the value of a column to its DEFAULT if the INSERT value happens to be an empty string.

My TRIGGER looks like this:

Answer 1

This should work for you

SET NEW.a = DEFAULT(NEW.a)

EDIT: It looks like that doesn't work.

Use this workaround

IF NEW.a = '' THEN
   SELECT COLUMN_DEFAULT INTO @def
   FROM information_schema.COLUMNS
   WHERE
     table_schema = 'database_name'
     AND table_name = 'your_table'
     AND column_name = 'a';
   SET NEW.a = @def;
END IF;

You can also try

SET NEW.a = DEFAULT(table_name.a)