1. A method for constructing abstract queries defined by a plurality of logical fields which map to a plurality of physical entities of physical data having a particular physical data representation in a database stored on a computer server having a memory and one or more processors, wherein each of the plurality of physical entities is a table in the database, the method comprising: receiving user input via a user interface, the input comprising a reference to a model entity definition comprising two or more logical fields, wherein a model entity corresponding to the model entity definition is selected as a focus for an abstract query the abstract query being composed from the plurality of logical fields via the user interface, each logical field providing a query component available to be included in an abstract query specifying one of a condition for the abstract query or an output field of the abstract query, and wherein each logical field includes a logical field name used to identify the logical field in the user interface and an access method selected from at least two distinct access method types, wherein the access method specifies a mapping between a respective logical field and one of the physical entities of physical data; and based on the model entity definition, selectively adding at least one logical field to the abstract query, wherein selectively adding the at least one of logical field comprises: determining, based on the model entity definition of the selected model entity, at least one logical field required as an output field for an abstract query of the selected model entity, determining whether the at least one logical field is already present as an output field in the abstract query, and if not, adding the at least one logical field to the abstract query.