title: Error report - ORA-00904: : invalid identifier 00904. 00000 - "%s: invalid identifier"
body: <p>This is my SQL Oracle script and I cannot figure out why I keep getting the following error when I try and run this code:
  I keep getting this exact code on each table I try to run. Can anyone point me in the right direction as to why my code will not run? I have tried researching this myself ALL DAY LONG and cant get it.** </p>
  
  <pre><code>Error starting at line : 12 in command -
  CREATE TABLE COURSE (
  CRS_CODE        VARCHAR (8) NOT NULL,
  CRS_DESCRIPTION VARCHAR (35) NOT NULL,
  CONSTRAINT    CRS_CREDIT    NOT NULL,
  CHECK (CRS_CREDIT IN (1,2,3,4)),
  PRIMARY KEY   (CRS_CODE))
  Error report -
  ORA-00904: : invalid identifier
  00904. 00000 -  "%s: invalid identifier"
  *Cause:    
  *Action:
  SQL&gt; 
  
  
  **CODE BEFORE ERROR:**
  /* This script file creates the following tables:*/
  /*COURSE, CLASS, ENROLL, STUDENT */
  
  set echo on;
  set serveroutput on ;
  
  /*DROP TABLE COURSE;
  DROP TABLE CLASS;
  DROP TABLE STUDENT;
  DROP TABLE ENROLL;*/
  
  CREATE TABLE COURSE (
  CRS_CODE        VARCHAR (8) NOT NULL,
  CRS_DESCRIPTION VARCHAR (35) NOT NULL,
  CONSTRAINT    CRS_CREDIT    NOT NULL,
  CHECK (CRS_CREDIT IN (1,2,3,4)),
  PRIMARY KEY   (CRS_CODE));
  
  CREATE TABLE CLASS (
  CLASS_CODE  NUMBER (5)  NOT NULL,
  CONSTRAINT CLASS_SECTION_Ck NOT NULL,
  CLASS_TIME  VARCHAR (25)    NOT NULL,
  CLASS_ROOM  CHAR (6),
  CHECK (CLASS_SECTION IN (1,2,3,4,5,6,7,8)),
  PRIMARY KEY (CLASS_CODE),
  FOREIGN KEY (CRS_CODE) REFERENCES COURSE (CRS_CODE));
  
  CREATE TABLE STUDENT (
  STU_NUM     INTEGER NOT NULL,
  STU_LNAME   VARCHAR (25) NOT NULL,
  STU_FNAME   VARCHAR (20) NOT NULL,
  STU_INIT    CHAR  (1),
  STU_DOB     DATE    NOT NULL,
  CONSTRAINTS STU_HRS_Ck  DEFAULT 0 NOT NULL,
  STU_CLASS   CHARACTER(2) REFERENCES "Fr", "So", "Jr", "Gr" NOT NULL,
  CONSTRAINT  STU_GPA_Ck  DEFAULT 0.00 NOT NULL,
  STU_PHONE   VARCHAR (4)  NOT NULL,
  PRIMARY KEY (STU_NUM),
  CHECK (STU_HRS &lt;= 0),
  CHECK (STU_HRS &gt;= 1000),
  CHECK (STU_GPA BETWEEN 0.00 AND 4.00));
  
  CREATE TABLE ENROLL (
  ENROLL_GRADE_Ck     VARCHAR (1) REFERENCES "A","B","C","D","F","I","W", "Z", DEFAULT Z NOT NULL,
  FOREIGN KEY (STU_NUM) REFERENCES STUDENT (STU_NUM),
  FOREIGN KEY (CLASS_CODE) REFERENCES CLASS (CLASS_CODE),
  PRIMARY KEY (CLASS_CODE));
  
  commit;
  </code></pre>