Based on the fact that your prior DB experience covers three different "brands" of DB servers already (and apart from the comments above about the likely similarity between Sybase and some MS SQL server you already know about), you can certainly apply and play up your strengths in terms of flexibility regarding DB environment.

An intelligent hiring manager should recognize that presence of a particular DB brand name on a resume is of secondary importance, compared to clear evidence of breadth and depth of DB experience, regardless of server brand. So try to give a brief summary of the things you handled in your DB exploits. That is, without being too verbose, give the resume reader a sense of the roles you're comfortable with (schema design? integration with external processes? UI development? DBA?).