The SQL language standard has grown from a modest SQL'92 document of less then a 100 pages to the latest SQL:2008 >4000 page description comprised of the following volumes:
The MonetDB SQL implementation is based on SQL 2003 and newer standards with a limited extension to features found elsewhere.
The tables below illustrates the (un)supported features in the latest stable distribution release. Beware that some of the features are technically impossible to support due to the design of MonetDB or would cause excessive performance consequences. Migration from your current database system to MonetDB may require adjustment of the schema definition and query formulation. A comparison table for most actively used features is given in the SQL compatibility wikibook.
Every SQL implementation differs in minor / major areas from the SQL standard. This calls for using middleware to translate queries, or even manually rewrite them according to the DBMS specifics.
A synopsis of the builtin functionality and comparison with related products, such as Postgresql, MySQL, and several commerical systems can be found in the SQL dialects book