SQL

postgres add not null to existing column

ALTER TABLE table_name ALTER COLUMN column_name SET NOT NULL;

postgresql change column to not null

-- To change a column to NOT NULL:
ALTER TABLE products ALTER COLUMN product_no SET NOT NULL;

alter column set not null to null postgres

ALTER TABLE person ALTER COLUMN phone DROP NOT NULL;

change from not null postgresql

ALTER TABLE table_name ALTER COLUMN column_name DROP NOT NULL;