A data-flow graphical user interface for querying a scientific database

We describe the design principles and functionality of a visual query language called See QL that represents data retrieval and analysis operations as a data-flow graph. A query is viewed as a sequence of relational algebra and other data transformation operations applied to database tables. The language is well-suited for large-scale scientific database applications, where data analysis is a major component and the typical queries or data retrieval patterns are unrestricted. The language provides a flexible yet easy-to-use environment for database access and data analysis for non-programmer research scientists. We have implemented this language in a system being used in a long-term data-intensive highway pavement research project (MnRoad) conducted by the Minnesota Department of Transportation