The resulting data set should be the same in both cases, but you are correct that the SQL optimizer might decide to choose different paths to resolve the query.

FYI - in Sybase multi-table queries are optimized 4 tables at a time (by default - this is configurable for recent versions of ASE (12.0 and later, IIRC)). It should be noted that query optimization (and understanding why the server decides to use a certain query plan) is a bit of a black art, especially when working on really large data sets.

Michael