title: how to retrieve rows which contains only number?
body: <p>I have a table tab1 with structure as-</p>
  
  <pre><code>+-----------+--------+
  |columnName |datatype|
  +-----------+--------+
  |col1       |VARCHAR |
  +-----------+--------+
  |col2       |VARCHAR |
  +-----------+--------+
  |col3       |VARCHAR |
  +-----------+--------+
  |col4       |VARCHAR |
  +-----------+--------+
  |col5       |VARCHAR |
  +-----------+--------+
  </code></pre>
  
  <p>and sample data as</p>
  
  <pre><code>+----+-------+----+----+----+
  |col1|col2   |col3|col4|col5|
  +----+-------+----+----+----+
  |11  |aaaaaaa|aaaa|aaaa|1111|
  +----+-------+----+----+----+
  |22  |bbbbbbb|bbbb|bbbb|2a2s|
  +----+-------+----+----+----+
  |33  |ccccccc|cccc|cccc|a312|
  +----+-------+----+----+----+
  |44  |ddddddd|dddd|dddd|4444|
  +----+-------+----+----+----+
  </code></pre>
  
  <p>Now i want to retrieve only those rows having col5 with only numbers ( like 1st and 4th row). How to write the query in oracle and teradata?</p>