Oracle检查约束违规

Question

I created a constraint on the date column of the table X . When I created a check constraint on date as date > '01-jan-2000' there is an error message (" Check constraint violated "). When I tried again to check the date if it comes after 1996 ( date > '01-jan-1996' ), it worked well.

Is there a reason for it?

I used this code:

ALTER TABLE X 
ADD CONSTRAINT DATE_CONST CHECK(DATE>'01-JAN-2000')     --  ERROR

ALTER TABLE X 
ADD CONSTRAINT DATE_CONST CHECK(DATE>'01-JAN-1996')     --  WORKED

Answer 1

there are two things you are done wrong. a) You can not assing name to column keyword like "DATE". b) you must to convert date when you add CONSTRAINT like this :

ALTER TABLE test ADD CONSTRAINT DATE_CONST CHECK(testdate>to_date('01-JAN-2000', 'dd-mon-yyyy'));

http://sqlfiddle.com/#!4/98198/9 is example of this question.

Edit : If your table has record before specified date, Check constraint will be compiled but it will be invalid. You must be update before specied date records to newly date.