Dfyjkt

I'm trying to create a table in Oracle 11g, but got ORA-00904 error. The syntax for creating the table is:

CREATE TABLE Worker(
nif VARCHAR2(9 CHAR) CONSTRAINT PK_Nif PRIMARY KEY,
nameworker VARCHAR2(50 CHAR) CONSTRAINT NN_NameWorker NOT NULL,
specialty VARCHAR2(50 CHAR) CONSTRAINT NN_Specialty NOT NULL,
CONSTRAINT CH_Speciality CHECK (speciality ='ENGINEERING' OR speciality= 'SUPPORT' OR speciality='DEVELOPMENT'),
yearsold INTEGER,
CONSTRAINT CH_Years CHECK (yearsold >= 1),
CONSTRAINT NN_Years NOT NULL,
nifCompany VARCHAR2(9 CHAR) CONSTRAINT NN_NifCompany NOT NULL,
CONSTRAINT FK_NifCompany FOREIGN KEY (nifCompany) REFERENCES Company(nif)
);

And the error I got is:

ORA-00904: : invalid identifier
00904. 00000 - "%s: invalid identifier"
*Cause: 
*Action:

I don't know where the error is.

You have a couple of problems; the immediate cause of the error is this line:

CONSTRAINT NN_Years NOT NULL,

which based on the earlier naming you probably meant to include inline with the column definition:

yearsold INTEGER CONSTRAINT NN_Years NOT NULL,
CONSTRAINT CH_Years CHECK (yearsold >= 1),

The second problem is that you've got inconsistent names, specialty in the column definition vs. speciality in the check constraint; so you need to fix the column and not-null constraint names:

speciality VARCHAR2(50 CHAR) CONSTRAINT NN_Specialty NOT NULL,

Fixing those things, and assuming you do have a Company table with a matching PK for the FK this specifies, gives you:

CREATE TABLE Worker(
 nif VARCHAR2(9 CHAR) CONSTRAINT PK_Nif PRIMARY KEY,
 nameworker VARCHAR2(50 CHAR) CONSTRAINT NN_NameWorker NOT NULL,
 speciality VARCHAR2(50 CHAR) CONSTRAINT NN_Specialty NOT NULL,
 CONSTRAINT CH_Speciality CHECK (speciality = 'ENGINEERING'
 OR speciality = 'SUPPORT' OR speciality = 'DEVELOPMENT'),
 yearsold INTEGER CONSTRAINT NN_Years NOT NULL,
 CONSTRAINT CH_Years CHECK (yearsold >= 1),
 nifCompany VARCHAR2(9 CHAR) CONSTRAINT NN_NifCompany NOT NULL,
 CONSTRAINT FK_NifCompany FOREIGN KEY (nifCompany) REFERENCES Company(nif)
);

Table WORKER created.

desc worker

Name Null? Type 
---------- -------- ----------------- 
NIF NOT NULL VARCHAR2(9 CHAR) 
NAMEWORKER NOT NULL VARCHAR2(50 CHAR) 
SPECIALITY NOT NULL VARCHAR2(50 CHAR) 
YEARSOLD NOT NULL NUMBER(38) 
NIFCOMPANY NOT NULL VARCHAR2(9 CHAR) 

I think the issue is that you are specifying constraint name during column definition. You cannot do that. You should specify constraints differently if you want to give them name.
Try :

CREATE TABLE Worker(
nif VARCHAR2(9 CHAR) ,
nameworker VARCHAR2(50 CHAR) ,
specialty VARCHAR2(50 CHAR),
CONSTRAINT CH_Speciality CHECK (speciality ='ENGINEERING' OR speciality= 'SUPPORT' OR speciality='DEVELOPMENT'),
yearsold INTEGER,
CONSTRAINT CH_Years CHECK (yearsold >= 1),
CONSTRAINT NN_Years check(yearold is NOT NULL),
nifCompany VARCHAR2(9 CHAR) ,
CONSTRAINT FK_NifCompany FOREIGN KEY (nifCompany) REFERENCES Company(nif),
CONSTRAINT PK_Nif PRIMARY KEY(nif),
CONSTRAINT NN_NameWorker check(nameworker is NOT NULL),
CONSTRAINT NN_Specialty check(specialty is NOT NULL),
CONSTRAINT NN_NifCompany check(nifCompany is NOT NULL)
);

Let me know if you face further issues