Options for eliminating NULLable columns from a DB model (in order to avoid SQL's three-valued logic)?

Question

Some while ago, I\'ve been reading through the book SQL and Relational Theory by C. J. Date. The author is well-known for criticising SQL\'s three-valued logic (3VL).

Answer 1

You can eliminate null in the output as well by using COALESCE.

SELECT personid  /*primary key, will never be null here*/
       , COALESCE(name, 'no name') as name
       , COALESCE(birthdate,'no date') as birthdate
FROM people

Not all databases support COALESCE, but almost all have a fallback option called
IFNULL(arg1, arg2) or something simular that will do the same (but only for 2 arguments).