ASE implements a subset of SQL 92 and isn’t 100% compliant with the SQL 92 standard (no DBMS on the planet is btw).
SQL99 compliance isn’t seriously being looked at by the major commercial DBMS vendors. Disregarding the fact the the SQL standards aren’t all they are cracked up to be, the vendors have too much invested in their own proprietary SQL variants (and other components) to be 100% compliant. If they were 100% compliant with the SQL92/99/whatever standard, then wholesale migrations from one vendor to another would take place.
I believe as time goes forward the opensource DBMSs (PostgreSQL, MySQL, etc) may become far more compliant with the standards than the commercial vendors as vendor lock in doesn’t mean as much to them.
Look into what the vendors (, MS, IBM,etc) are saying what constitutes as “compliance”. Ask each vendor what parts of the SQL99 standard they will be implementing and which parts they won’t be. If any vendor says that they are 100% compliant with the SQL92 or SQL99 ANSI standard, then that particular person is lying to you. Granted, that person may have been told their DBMS was 100% compliant and believes it. An honest vendor says that they comply with features X,Y and Z of the SQL 92 or SQL 99 standards.
Personally, I have found no significant movement by any of the commercial DBMS vendors to implement the SQL99 standard. So far it has just been lip service IMHO.