title: A non-numeric character was found where a numeric was expected
body: <p>when trying to add new rows I get "A non-numeric character was found where a numeric was expected", should I change one of data types?
  Data types in "tables"</p>
  
  <pre><code>CREATE TABLE TITLES
  (
  TITLE_ID                       VARCHAR2(6) NOT NULL,
  TITLE                          VARCHAR2(80) NOT NULL,
  CATEGORY                       CHAR(12) NOT NULL, 
  PUB_ID                         NUMBER(4) NULL, 
  PRICE                          INTEGER NULL,
  ADVANCE                        INTEGER NULL,
  TOTAL_SALES                    INTEGER NULL,
  NOTES                          VARCHAR2(200) NULL, 
  PUBDATE                        DATE NOT NULL,
  CONTRACT                       INTEGER NOT NULL,
  PRIMARY KEY (TITLE_ID),
  FOREIGN KEY (PUB_ID) REFERENCES PUBLISHERS(PUB_ID)
  );
  </code></pre>
  
  <p>Query:</p>
  
  <pre><code>INSERT INTO TITLES (TITLE_ID,TITLE,CATEGORY,PUB_ID,PRICE,ADVANCE,TOTAL_SALES,NOTES,PUBDATE,CONTRACT) VALUES ('PC8888','Secrets of Silicon Valley','popular_comp',1389,20,8000,4095,'Muckraking reporting by two courageous women on the worlds largest computer hardware and software manufacturers.','12-JUN-87',1);
  </code></pre>
  
  <p>Error report -
  SQL Error: ORA-01858: a non-numeric character was found where a numeric was expected
  01858. 00000 -  "a non-numeric character was found where a numeric was expected"
  *Cause:    The input data to be converted using a date format model was
             incorrect.  The input data did not contain a number where a number was
             required by the format model.
  *Action:   Fix the input data or the date format model to make sure the
             elements match in number and type.  Then retry the operation.</p>