You can use various tools and methods to detect and analyze null values, such as SQL queries ... as establishing default values in dimension tables, employing surrogate keys for unknown values ...

In SQL we support non-standard clause called ON CONFLICT / OR. It is not a separate clause which can appear in INSERT/UPDATE statements or as a column option in CREATE TABLE statements. See examples ...

INSERT INTO countries (COUNTRY_ID, COUNTRY_NAME, REGION_ID) VALUES ('VI', 'Vietnam', 3); -- 2. Insert one row into the table countries against the columns country_id and country_name INSERT INTO ...