Java Database Connectivity (JDBC)

There are a number of embedded open source databases for Java . However, some of the major database vendors such as DB2, contain their own way of doing things. For example in DB2 if you only want the first 4 rows in a query, you append the syntax: "FETCH FIRST 4 ROWS ONLY" to the SQL query. I am wondering which embedded database uses as close to DB2 syntax and concepts as possible?

Failing that, do any of the open-source embedded DB's mirror any of the major databases Oracle, SQLServer etc. closely

Thanks in advance,