title: Oracle: year must be between -4713 and +9999, and not be 0
body: <p>I have an Oracle table like this</p>
  
  <pre><code>|---------------------------------|
  |EMPNO |    HIREDATE  | INDEX_NUM |  
  |---------------------------------|  
  |1     |   2012-11-13 | 1         |
  |2     |   2          | 1         |
  |3     |   2012-11-17 | 1         |
  |4     |   2012-11-21 | 1         |
  |5     |   2012-11-24 | 1         |
  |6     |   2013-11-27 | 1         |
  |7     |   2          | 2         |
  |---------------------------------|
  </code></pre>
  
  <p>I am trying to execute this <code>query</code> against this table</p>
  
  <pre><code>SELECT hiredate
    FROM admin_emp
    WHERE TO_DATE('hiredate','yyyy-mm-dd') &gt;= TO_DATE('2012-05-12','yyyy-mm-dd');
  </code></pre>
  
  <p>But getting the error</p>
  
  <pre><code>ORA-01841: (full) year must be between -4713 and +9999, and not be 0
  </code></pre>
  
  <p>Any idea..? What is the issue here?</p>
  
  <p>query base:</p>
  
  <pre><code>CREATE TABLE admin_emp (
           empno      NUMBER(5) PRIMARY KEY,
           hiredate   VARCHAR(255),
           index_num NUMBER(5));
  
  
  insert into admin_emp(empno,hiredate,index_num) values
  (1,'2012-11-13',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (2,'2',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (3,'2012-11-17',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (4,'2012-11-21',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (5,'2012-11-24',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (6,'2013-11-27',1);
  insert into admin_emp(empno,hiredate,index_num) values
  (7,'2',2);
  </code></pre>