1. A method of enforcing database predicate constraints on database accesses, comprising: receiving, by a database management system stored on a non-transitory computer readable medium and executable by a processor, a database query; parsing, by the database management system, the query based on query constraints defined in system tables, wherein the query constraints require a where clause in the query and limit the where clause in the query; examining, by the database management system, the query for the existence of the where clause; examining, by the database management system, the where clause to determine compliance with the query constraints defined in the system tables; validating the syntax of the query before executing the query; executing, by the database management system, the query only when the query contains the where clause, the where clause complies with the query constraints defined in the system tables, and the query complies with user classification constraints stored in tables of the database management system to apply different levels of access for queries to different user classifications, wherein the user classification constraints are applied to client devices; and rejecting, by the database management system, the query when the query does not contain the where clause, or when the query does contain the where clause and the where clause does not comply with the query constraints defined in the system tables, or when the query does not comply with the user classification constraints.