THe HSQLDB changelog states that ROWNUM() was added in v2.2.0 which I am using without any problems when running integration tests against the in-memory HSQLDB.
However I want to run the same tests against a real Oracle 10g database, but the query fails because the pseudo-column is called ROWNUM. Is there an easy way write a single query string that works in both environments?
The ROWNUM() function is available by default in HSQLDB 2.2.x and later. If you enable Oracle syntax compatibility mode, you can also use ROWNUM.
This statement enables it:
SET DATABASE SQL SYNTAX ORA TRUE
Or use the connection property sql.syntax_ora=true
来源：https://stackoverflow.com/questions/6612862/hsqldb-rownum-compatibility-with-oracle