16. A method of checking user authorization to access a database comprising: receiving a query; producing an execution plan, for the query, that indicates a database structure plan identity of a database structure used in the course of processing of the query, that indicates a schema plan name of a schema containing a schema table used during execution of the query within the database according to the execution plan, and that indicates a type of access to the indicated database structure performed in the course of processing the query; receiving an access rule applicable to a user associated with the query, the access rule indicating a rule identity of a rule database structure, a second schema name of a second schema containing a second schema table, and a type of access to the rule database structure and that specifies an action; determining whether the database structure plan identity of the database structure matches the rule identity of the rule database structure specified by the access rule, whether the schema containing the schema table indicated by the schema plan name of the execution plan matches the second schema containing the second schema table indicated by the second schema name of the access rule, and whether the type of access indicated by the execution plan matches the type of access indicated by the access rule; and performing the action indicated by the access rule in response to a determination that the database structure plan identity of the database structure indicated by the execution plan matches the rule identity of the rule database structure specified by the access rule, that the schema containing the schema table indicated by the schema plan name of the execution plan matches the second schema containing the second schema table indicated by the second schema name of the access rule, and that the access type indicated by the execution plan matches the access type specified by the access rule.
20. The method of claim 16 further including: rejecting the query in response to a determination that the database structure plan identity of the database structure indicated by the execution plan does not match the rule identity of the rule database structure specified by the access rule, that the schema containing the schema table indicated by the execution plan does not match the second schema containing the second schema table indicated by the access rule, or that the access type indicated by the execution plan does not match the access type specified by the access rule.