add not null constraint postgres code example
Example 1: postgres add not null to existing column
ALTER TABLE table_name ALTER COLUMN column_name SET NOT NULL;
Example 2: postgresql change column to not null
-- To change a column to NOT NULL:
ALTER TABLE products ALTER COLUMN product_no SET NOT NULL;
Example 3: postgresql add not null constraint
alter table users alter column email set not null;
Example 4: postgresql add not null and not empty constraint
ads character varying(60) NOT NULL CHECK (ads <> '')