default a column with empty string

Is there a way, via a SQL statement, to ensure a column's default value is an empty string开发者_如何学JAVA '' instead of NULL?

Yes - use a DEFAULT constraint:

DROP TABLE IF EXISTS `example`.`test`;
CREATE TABLE  `example`.`test` (
  `string_test` varchar(45) NOT NULL DEFAULT ''
) ENGINE=InnoDB DEFAULT CHARSET=latin1;