DROP TABLE cons_demo;

CREATE TABLE cons_demo (owner varchar2(100), object_name varchar2(128));

INSERT /*+ APPEND */ INTO cons_demo SELECT owner, object_name FROM dba_objects;
COMMIT;

SELECT COUNT(*) FROM cons_demo;
@x

CREATE INDEX idx1_cons_demo ON cons_demo(owner);

SELECT COUNT(*) FROM cons_demo;
@x

SELECT /*+ INDEX(cons_demo cons_demo(owner)) */ COUNT(*) FROM cons_demo;

ALTER TABLE cons_demo MODIFY owner NOT NULL NOVALIDATE;

INSERT INTO cons_demo VALUES (null, 'x');

SELECT COUNT(*) FROM cons_demo;
@x

ALTER TABLE cons_demo MODIFY owner NULL;
--ALTER TABLE cons_demo MODIFY owner NOT NULL VALIDATE;
--ALTER TABLE cons_demo MODIFY owner NOT NULL DEFERRABLE INITIALLY DEFERRED VALIDATE;
ALTER TABLE cons_demo MODIFY owner NOT NULL DEFERRABLE VALIDATE;

SELECT COUNT(*) FROM cons_demo;
@x


DROP TABLE cons_demo2;

CREATE TABLE cons_demo2 AS SELECT * FROM scott.emp;

ALTER TABLE cons_demo2 ADD CONSTRAINT c2 CHECK (SAL > 500);

SELECT * FROM cons_demo2 WHERE sal = 100;

@x