20. The computer-readable storage medium of claim 16 , wherein the abstract query comprises at least one selection criterion and a result specification.
16. A tangible computer-readable storage medium containing a program which, when executed by a processor, performs an operation of preventing alterations of data in a database when a query is executed against the database, the operation comprising: providing a logical representation of the data defining a plurality of logical fields abstractly describing a manner of accessing and exposing, via a user interface, associated physical entities of the data, wherein each of the plurality of logical fields include a reference to an access method selected from at least two different access method types; wherein the at least two different access method types are selected from the group comprising: (i) a simple access method which maps a respective one of the plurality of logical fields directly to a physical entity, (ii) a filtered access method which identifies a physical entity and provides rules used to define a subset of items within the physical entities, and (iii) a composed access method which computes a value for a respective one of the plurality of logical fields from one or more physical entities using an expression supplied as part of a composed access method definition; wherein each of the different access methods types defines a different manner of exposing the respective physical entities of the data; and wherein at least a portion of the plurality of logical fields include lock attributes referenced in order to lock the respective logical field; receiving an abstract query comprising at least one logical field of the portion of logical fields; in response to receiving the abstract query, locking the at least one logical field before executing the abstract query on the basis of the respective lock attributes of the at least one logical field; and unlocking at least one logical field after executing the abstract query.