A graphical query interface provides visual feedback to a user during the
construction of a query. In a first embodiment, the visual feedback helps
the user determine the quality of the query as the query is being built.
The relationship of columns in the database is graphically displayed to a
user. When the user selects a column in the database, a filtered display
mechanism displays only those columns or records that satisfy the portion
of the query already constructed. In a second embodiment, the visual
feedback eliminates some possible selections in the query tree due to
previously-made selections that eliminate the eliminated selections as
possibilities. In the second embodiment, the visual feedback mechanism
may function according to data values in columns, and may also function
according to known relationships between columns themselves.