Can't figure out the SQL code - sql

Question

CREATE TABLE empinf(
companyid varchar2(5) PRIMARY KEY,
companyname varchar2(30) NOT NULL,
emailid varchar2(20) REFERENCES usrinf(emailid),
Mobile number CONSTRAINT moc CHECK(LENGTH(Mobile)=10),
city varchar2(20),
industrytype varchar2(20),
functionalarea varchar2(20),
membershipplan varchar2(20) CONSTRAINT cmp CHECK(membershipplan in ('TRIAL','PREMIUM MONTHLY','PREMIUM YEARLY')),
dateofsignup date DEFAULT SYSDATE CONSTRAINT chd CHECK( dateofsignup>=SYSDATE ),
dateofrenewal date generated always as
(CASE
WHEN membershipplan='TRIAL' THEN SYSDATE+14
WHEN membershipplan='PREMIUM MONTHLY' THEN SYSDATE+30
WHEN membershipplan='PREMIUM YEARLY' THEN SYSDATE+365
ELSE SYSDATE
END
) virtual,
renewalstatus varchar2(20) CONSTRAINT chrs CHECK(renewalstatus in('ACTIVE','EXPIRED')),
CONSTRAINT mun UNIQUE(Mobile)
)
This code is to be generated in Oracle Express 11G, I am unable to figure out what's wrong with code, it shows 'missing paranthesis error'.

Answer 1

As far as I know, in a virtual column you need to define a deterministic function (a one which return same value, irrespective of when you call it.
You could try to use dateofsignup instead of SYSDATE inside case .
dateofrenewal date generated always as
(CASE
WHEN membershipplan='TRIAL' THEN dateofsignup+14
WHEN membershipplan='PREMIUM MONTHLY' THEN dateofsignup+30
WHEN membershipplan='PREMIUM YEARLY' THEN dateofsignup+365
ELSE dateofsignup
END
) virtual
Or you can remove it from table and use a view.
I forgot the other error (I was concentrating on the first one, so I apologize for the miss). As Thorsten say in other answer, you have a problem to set a check constraint for datesignup in that way.
Other that solution Torstein suggested, another solution could be to add another column (eg. DATE_INSERT DATE DEFAULT SYSDATE)
and write the constraint changing datesignup definition as
dateofsignup date DEFAULT SYSDATE
and add
ALTER TABLE empinf ADD CONSTRAINT chd CHECK( dateofsignup>=DATE_INSERT)
Your missing parenthesis error can be caused by your tries, while you commented some parts of the code.
Tip: I agree with g00dy comment above: create table basic structure with one command, then add constraint with separate commands.

Answer 2

It is strange you are getting a "missing paranthesis" error. Maybe the tool you are using to execute the statement swallows the last paranthesis?
I am getting "ORA-02436: date or system variable wrongly specified in CHECK constraint"
CONSTRAINT chd CHECK( dateofsignup>=SYSDATE )
You cannot use SYSDATE in a check constraint, as SYSDATE is subject to change. A check constraint must be stable and must not depend on the current time, a current session setting or the like. You'd need a trigger to do what you want to do.
After removing that check constraint I get "ORA-54002: only pure functions can be specified in a virtual column expression", which is about for the same reason.
dateofrenewal date generated always as
(CASE
WHEN membershipplan='TRIAL' THEN SYSDATE+14
...
A virtual column must be stable and can only depend on other columns, not on the current time, a current session setting or the like. You probably want dateofrenewal to be calculated based on dateofsignup instead.