Where filter expression: how to express a search expression in a text field

Hello,

I am trying to understand how to create a search expression for filtering document content based on text field containing some expression/regular expression.

For this I use where field contains ...

How to build a search expression, where can we find a description of possibilities?

In my particular case, database used for integrity is Oracle.

Thanks in advance for any idea, help.

Regards.

Marc.