SQL oracle将检查约束添加到现有表

Question

Im using SQL/PL developer and I have a table named Appeal, that has 2 attributs OpenDate and CloseDate. And I want to add a constraint to ensure that open date will be smaller than close date. I have a lot of records in this table.

this is my code:

alter table appeal
add constraint Check_Dates
check (OpenDate < CloseDate)

and I get en error saying: ORA-02293: cannot validate (STSTEM.CHECK_DATES) - check constraint violated

any ieads? Thanx

Answer 1

Your constraint looks right, I have tested it:

create table appeal ( OpenDate date,  CloseDate date);

alter table appeal
add constraint Check_Dates
check (OpenDate < CloseDate);

insert into appeal values ( sysdate, sysdate - 1 );

And here the result:

Schema Creation Failed: ORA-02290: check constraint (USER_4_44096.CHECK_DATES) violated

Problem is than you have already rows with OpenDate < CloseDate values in your database. Fix it before create constraint. Look behavior changing sentences order:

create table appeal ( OpenDate date,  CloseDate date);

insert into appeal values ( sysdate, sysdate - 1 );

alter table appeal
add constraint Check_Dates
check (OpenDate < CloseDate);

And here your issue:

Schema Creation Failed: ORA-02293: cannot validate (USER_4_E4450.CHECK_DATES) - check constraint violated

Answer 2

Try this alter table appeal add constraint Check_Dates check (OpenDate < CloseDate) ENABLE NOVALIDATE;

You will have check the previous data for errors but any new Data will fall under the CHECK