I'm getting strange behavior in defining LONG dataype one DB's CLOB column?
Can you elaborate on what this strange behaviour is? Any error messages you see will be most useful.
and 'can I use LONG data type (limit a 20000 chr) to handle a column defined as CLOB in db?>
Depends. Certainly not out-of-the-box.
Have you seen this ? http://fdegrelle.over-blog.com/article-2615079.html
It will also help to know what this CLOB column contents are. Plain text? XML?