update_date NOT NULL约束的数据库表设计最佳实践

Question

I have database table contains updated_date column as below.

CREATE TABLE table_name
(
  id character varying(20) NOT NULL,
  created_date timestamp NOT NULL,
  updated_date timestamp,
  isactive smallint DEFAULT 1,
  version smallint NOT NULL DEFAULT 0,
  CONSTRAINT table_name_pkey PRIMARY KEY (id)
);

Please suggest updated_date timestamp NOT NULL is best practice?

Answer 1

It depends a lot on how you are going to use those columns.

I see nothing wrong with declaring the column NOT NULL and using the same created_date and updated_date when a record is created (I would have chosen names that do not contain “date” though).

I think that it is a good habit to have columns NOT NULL if that is possible for the application without bending its arm (a bad example would be using 1970-01-01 00:00:00 to represent missing data). It usually makes queries simpler and hence more efficient if they don't have to deal with NULL values.