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Create Relations

  Choose the create item from the Relation menu, a Relation Dialog appears for the creation of a new relation. The relation name, attribute list and tuples for the new relation may be entered (see figures8,9). The user may choose between two items [ Attributes or Data ( Tuples)] in the tabbed panel of the Relation Dialog and press the Add-Button, and an 'Add Attribute Dialog' or 'Add Tuple Dialog' appears for the insertion of an attribute or a tuple, respectively.

To add an attribute, the Attribute Name, the Attribute Type and the isConstraint flag need to be specified. The value of the isConstraint flag is set to be 'true' for a spatiotemporal attribute, or 'false' to a traditional (relational) attribute. The attribute appears in the attribute list of the 'Relation Dialog' after the user clicks the Ok-button in the 'Add Attribute Dialog.' To insert a tuple, the user may enter the tuple value in the textfield of the 'Add Tuple Dialog' and press the Ok-button. To save the relation and add it to the relation tree, the user may click the save-button. The tuples in the relation may be changed after the relation appears in the relation tree.

    
Figure 9: New Relation dialog of CDB


Figure 8: Add Attribute Dialog and
Add Tuple dialog of CDB


Yang Fuzheng
Tue Aug 20 18:48:50 EDT 2002