title: nextval must be declared
body: <p>I created a sequence as the below in oracle 12c with no problem,</p>
  
  <pre><code>CREATE SEQUENCE EMPLOYEE_SEQ
    START WITH 1
    MAXVALUE 9999999999999
    MINVALUE 1
    NOCYCLE
    CACHE 20
    NOORDER;
  </code></pre>
  
  <p>however, I get error which says <code>"Error(2,25): PLS-00201: identifier 'EMPLOYEE_SEQ.NEXTVAL' must be declared"</code> for the codes below</p>
  
  <pre><code>    CREATE OR REPLACE TRIGGER EMPLOYEE_TRG BEFORE INSERT ON EMPLOYEE REFERENCING 
      NEW AS NEW OLD AS OLD FOR EACH ROW
        BEGIN
          :new.EMPLOYEE_ID := EMPLOYEE_SEQ.nextval;
      END EMPLOYEE_TRG;
  </code></pre>
  
  <p>how can I fix this?</p>