title: Filter the rows with number only data in a column SQL
body: <p>I am trying to <code>SELECT</code> rows in a table, by applying a filter condition of identifying number only columns. It is a report only query, so we least bother the performance, as we dont have the privilege to compile a PL/SQL am unable to check by <code>TO_NUMBER()</code> and return if it is numeric or not.</p>
  
  <p>I have to achieve it in SQL. Also the column is having the values like this, which have to be treated as Numbers.</p>
  
  <pre><code>-1.0
  -0.1
  -.1
  +1,2034.89
  +00000
  1023
  </code></pre>
  
  <p>After ground breaking research, I wrote this.(Hard time)</p>
  
  <pre><code>  WITH dummy_data AS
    ( SELECT '-1.0' AS txt FROM dual
    UNION ALL
    SELECT '+0.1' FROM dual
    UNION ALL
    SELECT '-.1' FROM dual
    UNION ALL
    SELECT '+1,2034.89.00' FROM dual
    UNION ALL
    SELECT '+1,2034.89' FROM dual
    UNION ALL
    SELECT 'Deva +21' FROM dual
    UNION ALL
    SELECT '1+1' FROM dual
    UNION ALL
    SELECT '1023' FROM dual
    )
  SELECT dummy_data.*,
    REGEXP_COUNT(txt,'.')
  FROM dummy_data
  WHERE REGEXP_LIKE (TRANSLATE(TRIM(txt),'+,-.','0000'),'^[-+]*[[:digit:]]');
  </code></pre>
  
  <p>I got this.</p>
  
  <pre><code>TXT           REGEXP_COUNT(TXT,'.')
  ------------- ---------------------
  -1.0                              4
  +0.1                              4
  -.1                               3
  +1,2034.89.00                    13 /* Should not be returned */
  +1,2034.89                       10
  1+1                               3 /* Should not be returned */
  1023                              4
  
  7 rows selected.
  </code></pre>
  
  <p>Now terribly confused with 2 Questions.</p>
  
  <p>1) I get <code>+1,2034.89.00</code>  too in result, I should eliminate it. (means, two decimal points) Not just decimal point, double in every other special character (-+,) should be eliminated)<br><br>
  2) To make it uglier, planned to do a <code>REGEXP_COUNT('.') &lt;= 1</code>. But it is not returning my expectation, while selecting it, I see strange values returned.</p>
  
  <p>Can someone help me to frame the <code>REGEXP</code> for the avoiding the double occurences of <code>('.','+','-')</code></p>