What's the point of “NOT NULL DEFAULT '' ”?

Question

I\'ve seen this on a lot of fields on a DB from a project I\'ve been working on, where a column will be defined not null, but will have an empty string as the default. what\'s t

Answer 1

There is a difference between a null value and an empty string - at least in SQL.

SELECT LENGTH('tata');
4

SELECT LENGTH(NULL);
NULL

SELECT LENGTH('tata')-LENGTH('');
4

SELECT LENGTH('tata')-LENGTH(NULL);
NULL