Oracle: SQL query that returns rows with only numeric values

Question

I have a field (column in Oracle) called X that has values like \"a1b2c3\", \"abc\", \"1ab\", \"123\", \"156\"

how do I write an sql query that returns me only the X

Answer 1

What about 1.1E10, +1, -0, etc? Parsing all possible numbers is trickier than many people think. If you want to include as many numbers are possible you should use the to_number function in a PL/SQL function. From http://www.oracle-developer.net/content/utilities/is_number.sql:

CREATE OR REPLACE FUNCTION is_number (str_in IN VARCHAR2) RETURN NUMBER IS
   n NUMBER;
BEGIN
   n := TO_NUMBER(str_in);
   RETURN 1;
EXCEPTION
   WHEN VALUE_ERROR THEN
      RETURN 0;
END;
/