An advanced type of
query uses operators on successive selection sets to return a new
set of objects or records, which then can be further refined by the
same process.
Link
Select is an advanced implementation of the Query Editor that constructs
iterative selection sets of graphical objects and database records.
Link Select creates an ongoing selection set
that you refine with additional information through a running iterative
process. You begin either by constructing a query or by selecting
graphical objects. This initial selection set is referred to as
set A. You can now select additional graphical objects or issue a
query to further refine your selection set. This second selection
set is referred to as set B. You must establish a relationship between
set A and set B to further refine the selection set. The following
relationships or set operations are available:
- Select. Creates
an initial query or selection set. This selection set can be refined
through subsequent Link Select operations.
- Union. Adds
the results of the new query or selection set to the running selection
set. This operation returns all records or objects that are members
of set A or set B.
- Intersect. Returns
the intersection of the existing running selection and the results
of the new query or drawing selection. This operation returns all
records or objects that are members of set A and set B.
- Subtract A - B. Subtracts
the results of the new query or drawing selection from the existing
running selection.
- Subtract B - A. Subtracts
the existing running selection from the results of the new query
or drawing selection.
After you apply one of the set operations, the
returned results become the new running selection and are assigned
to set A. You can continue the iterative process by creating additional
B sets to further refine your Link Select set.
To use Link Select
- In the dbConnect Manager, in the tree
view, right-click a link template. Click Link Select.
- Select the Select option from the Do
list.
- Select a link template from Using.
- Select one of the following options:
- Use Query. Constructs
a query using one of the tabs in the Query Editor.
- Select in Drawing. Closes
the dialog box temporarily so that you can select graphical objects
in the drawing. When you select the Select in Drawing option, the
Execute button changes to Select.
- Click either Execute or Select to add
your query or graphical object selection set to the Link Select
operation.
- Select a Link Select operation from the
Do list: Union, Intersect, Subtract A-B, or Subtract B-A.
- Repeat steps 3 through 5 to add set B
to the Link Select operation.
- Select one or both of the following options
and click Finish to complete the Link Select operation:
- Indicate Records in Data
View. Returns the results of the current Link Select
operation in the Data View window when you click Finish. You can perform
further Link Select iterations by clicking the Return to Link Select button
in the Data View window.
- Indicate Objects in Drawing. Creates
a selection set of linked graphical objects in the drawing area
when you click Finish. You can perform further Link Select iterations
by pressing Enter at the command prompt.
NoteIt is recommended
that you turn off the Indicate Records in Data View option if you
are performing a Link Select operation on links from more than one database
table. Link Select only displays records from the table that the
current link template references. This limitation can cause misleading
results to be returned to the Data View window.
CommandsDBCONNECT
Provides an interface
to external database tables.
