title: SQL convert varchar2 to number
body: <p>I have this table X with only one column, BMI. All values are of datatype VARCHAR2(5 byte).</p>
  
  <pre><code>BMI
  ---
  24.81
  34.23
  23.21
  ...
  </code></pre>
  
  <p>Question how to convert these values into number? I've tried </p>
  
  <pre><code>SELECT to_number(BMI) FROM X;
  </code></pre>
  
  <p>But i get the error 'invalid number', don't know why...</p>
  
  <p>Thanks in advance.</p>