Last night, while I was coding a new program, I realized that I created wrong constraints. Then I found two methods to fix my mistake.
1- Drop table and create the table again. I think, this is not a desired solution.
DROP TABLE table_name CASCADE CONSTRAINTS;
2- If you have lots of constraints, you cannot write one by one this line.. constraint_names are also so long 🙂
ALTER TABLE table_name DROP CONSTRAINT constraint_name;
So, you can use this procedure;