Figure 7: Example Query with tables visualization (click on image for larger version)
The tables visualization method presents the results of queries as tables, with one column for each projected field. The user activates the method with the Tables Visualization Tool and then clicks on the fields to be projected. Note that fields in multiple classes can be selected in the same query. Assume, for example, that the user needs to correlate values between Segment objects and their referenced Fields. The screenshot of Figure 6 shows a sample query that can be described as follows:For each Segment object, retrieve the referenced Field objects and show the camCol and nChild fields.
When the query is executed, a separate window will appear to visualize the returned values as shown in Figure 8. The visualization window appears before the query is completed and is updated continuously as more result data are fetched from the database. Note that the final table will contain one row per Segment->Field pair and the same camCol value will thus be repeated across multiple rows.
The table window provides the following functionality:
Refresh
Re-execute the query that produced the table and update the view with the new results.
Select
Select the query that generated these results. The query is selected in the history window and shown in the canvas.
Sort
Sort the results on the selected columns. The user selects columns by pressing and holding the <Shift> button and by clicking on the appropriate column headers; the number that appears next to each header signifies the rank of the column in the comparison order. Note also that the user can perform a single column sort by clicking on the header of the column (without pressing <Shift>)
Pause/Continue
Freeze the visualization in its current state. The corresponding query is paused and no new results are fetched from the database. By pressing the button again, the user causes the query to resume execution and the visualization is updated with the new results.
Stop
Stop the execution of the query. This cancels the query on the database server and the visualization is not be updated with any new results thereof. From this state, the user can only restart the visualization from the beginning with the refresh button.
Save
Save the results of the query in a file, as space separated values.