Dynamic graphical database query interface

An apparatus comprising:

• at least one processor;
• a memory coupled to the at least one processor;
• a database residing in the memory;
• and
• a graphical query interface residing in the memory and executed by the at least one processor, the graphical query interface displaying in a first window a graphical representation of a plurality of user-selectable icons, each user-selectable icon corresponding to a column defined in the database, the graphical representation including at least one line connecting the plurality of user-selectable icons to represent at least one relationship between columns in the database represented by two of the plurality of icons connected by a line, and in response to a user selection of an icon in the graphical representation corresponding to a first column in a first step in building a query, the graphical query interface altering the graphical representation to make at least one icon corresponding to at least one different column in the graphical representation unavailable for selection by the user in a subsequent step in building the query according to at least one predefined rule for the first column that specifies at least one restriction between the first column and the at least one different column, the graphical query interface during display of the graphical representation in the first window further displaying in a second window at least one selectable value corresponding to values in the database corresponding to the first column.